DE69330414T2 - A process for producing a silver halide photographic light-sensitive material - Google Patents

Description

The present invention relates to a process for producing a silver halide photographic light-sensitive material.

Specifically, the present invention relates to a process for producing a silver halide photographic light-sensitive material having improved photographic properties such as fog and sensitivity.

In recent times, the requirements for photographic silver halide emulsions have become increasingly higher, and high demands have been placed on photographic properties such as high sensitivity and low fog.

Regarding the uniformity of chemical sensitization, it is considered preferable that the silver iodide (iodide ion) contents are uniform within an individual grain as well as between grains in order to increase the sensitivity of the grains.

EP-A-0 368 275 discloses a silver halide photographic emulsion and a silver halide photographic material comprising the emulsion, wherein the emulsion comprises silver halide grains having a first silver halide phase containing at least 3 mol% silver iodide and a completely uniform iodide distribution and a second silver halide phase having at least 5 dislocation lines.

EP-A-0 273 404 describes a photographic light-sensitive material comprising a support having at least one light-sensitive silver halide emulsion layer thereon, wherein the emulsion layer contains silver chlorobromide prepared in such a manner that regular silver halide crystal grains having no twin crystal face and containing 50 mol% or more of silver chloride are used as host grains, an organic compound is adsorbed on a surface of each of the host grains, and sulfur plus gold sensitization is carried out either during or after halide conversion in the presence of a bromide, and a process for developing a photographic light-sensitive material.

EP-A-0 534 283, which is included in the state of the art according to Article 54(3) EPC for the contracting states DE, FR and GB, discloses a silver halide photographic light-sensitive material having at least one silver halide emulsion layer formed on a support, wherein the light-sensitive material has at least one layer containing a silver halide emulsion containing regular or tabular silver halide grains which have been chemically sensitized and/or spectrally sensitized with a specific methine compound.

JP-A-2-68538 (Japanese Patent Application No. 63-220187) discloses the technique of eliminating non-uniform distribution of halide within an individual grain and between grains by using a halogen ion-releasing agent or fine silver halide grains as a halogen ion source instead of an aqueous halogen salt solution conventionally used to form grains in the process of forming silver halide grains ("JP-A" means a published unexamined Japanese patent application).

However, the silver halide grains having regular crystal formed by using the technique disclosed in this publication are still unsatisfactory in meeting the above requirements, i.e., sufficient reduction in fog and high sensitivity.

JP-A-2-68538 does not disclose that in order to prepare an emulsion improved in fog and sensitivity, it is important to form silver halide grains having regular crystal with a silver halide phase containing silver iodide while rapidly generating iodide ions.

The above object of the present invention is achieved by a process for producing a silver halide photographic light-sensitive material comprising at least one silver halide light-sensitive emulsion layer formed on a support, the emulsion layer containing at least one silver halide emulsion comprising regular crystal grains having a silver halide phase containing silver iodide, the silver halide phase having been formed while iodide ions are rapidly generated in the reactor vessel.

In one embodiment, 60% or more of the surface area of each regular crystal grain may be a (111) face or (100) face.

The iodide ions are generated from an iodide ion releasing agent added to the reaction vessel, and 100 to 50% of the iodide ion releasing agent completes the release of iodide ions within 180 continuous seconds in the reactor vessel. The iodide ions are generated from the iodide ion releasing agent by a reaction with an iodide ion release controlling agent, provided that if the iodide ion releasing agent is I(CH2)2COOH, the iodide ion release controlling agent is not Br(CH2)2SO3Na. The reaction can be expressed as a second order reaction which is substantially proportional to the concentration of the iodide ion releasing agent and the concentration of the iodide ion release controlling agent, and the rate constant of the second order reaction is 1,000 to 5 x 10-3 M-1 s-1

Generally, the iodide ion releasing agent is represented by Formula (I):

R-I

wherein R represents a monovalent organic radical which releases the iodine atom in the form of ions upon reaction with a base and/or a nucleophilic reagent.

The present invention is described in more detail below.

carbon atoms, a heterocyclic group having 4 to 30 carbon atoms, an acyl group having 1 to 30 carbon atoms, a carbamoyl group, an alkyl or aryloxycarbonyl group having 2 to 30 carbon atoms, an alkyl or arylsulfonyl group having 1 to 30 carbon atoms and a sulfamoyl group.

R is preferably one of the above groups having 20 or less carbon atoms, and most preferably one of the above groups having 12 or less carbon atoms.

Groups each having the number of carbon atoms falling within this range are preferred in terms of their solubility and the amount in which they are used.

It is also preferred that R is substituted, and examples of preferred substituents are as follows. These substituents may be further substituted with other substituents.

Examples of the substituents are a halogen atom (e.g. fluorine, chlorine, bromine or iodine), an alkyl group (e.g. methyl, ethyl, n-propyl, isopropyl, t-butyl, n-octyl, cyclopentyl or cyclohexyl), an alkenyl group (e.g. allyl, 2-butenyl or 3-pentenyl), an alkynyl group (e.g. propargyl or 3-pentynyl), an aralkyl group (e.g. benzyl or phenethyl), an aryl group (e.g. phenyl, naphthyl or 4-methylphenyl), a heterocyclic group (e.g. pyridyl, furyl, imidazolyl, piperidyl or morpholyl), an alkoxy group (e.g. methoxy, ethoxy or butoxy), an aryloxy group (e.g. phenoxy or naphthoxy), an amino group (e.g. unsubstituted amino, dimethylamino, ethylamino or anilino), an acylamino group (e.g. acetylamino or benzoylamino), a Ureido group (e.g. unsubstituted ureido, N-methylureido or N-phenylureido), a urethane group (e.g. methoxycarbonylamino or phenoxycarbonylamino), a sulfonylamino group (e.g. methylsulfonylamino or phenylsulfonylamino), a sulfamoylamino group (e.g. sulfamoyl, N-methylsulfamoyl or N-phenylsulfamoyl), a carbamoyl group (e.g. carbamoyl, diethylcarbamoyl or phenylcarbamoyl), a sulfonyl group (e.g. methylsulfonyl or benzenesulfonyl), a sulfinyl group (e.g. methylsulfinyl or phenylsulfinyl), an alkyloxycarbonyl group (e.g. methoxycarbonyl or ethoxycarbonyl), an aryloxycarbonyl group (e.g. phenoxycarbonyl), an acyl group (e.g. acetyl, benzoyl, formyl or pivaloyl), an acyloxy group (e.g. acetoxy or benzoyloxy), an amidophosphoryl group (e.g. N,N-diethylamidophosphoryl), an alkylthio group (e.g. methylthio or ethylthio), an arylthio group (e.g. phenylthio), a cyano group, a sulfo group, a carboxyl group, a hydroxy group, a phosphono group or a nitro group.

Particularly preferred substituents for R are a halogen atom, an alkyl group, an aryl group, an S- or 6-membered heterocyclic group containing at least one of O, N or S, an alkoxy group, an aryloxy group, an acylamino group, a sulfamoyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, an aryloxycarbonyl group, an acyl group, a sulfo group, a carboxyl group, a hydroxy group and a nitro group.

The most preferred substituents for R are a hydroxy group, a carbamoyl group, a lower alkylsulfonyl group and a sulfo group (including its salt) when substituted on an alkylene group, and a sulfo group (including its salt) when substituted on a phenyl group.

A compound represented by the formula (I) usable in the present invention is preferably a compound represented by the following formula (II) or the following formula (III).

A compound represented by formula (II) usable in the present invention is described below. Formula (II):

In formula (II), R₂₁ represents an electron withdrawing group, and R₂₂ represents a hydrogen atom or a substitutable group.

n₂ represents an integer from 1 to 6. n₂ is preferably an integer from 1 to 3 and particularly preferably 1 or 2.

The electron withdrawing group represented by R₂₁ is preferably an organic group having a Hammett value σp, σm or σi greater than 0.

The Hammett value σp or σm is described in "Structural Activity Correlation of Chemicals" (Nanko Do), page 96 (19979), and the Hammett value σi is described in the same Literature reference on page 105. Thus, the values can be selected based on these tables.

Preferred examples of R₂₁ are a halogen atom (e.g. fluorine, chlorine or bromine), a trichloromethyl group, a cyano group, a formyl group, a carboxylic acid group, a sulfonic acid group, a carbamoyl group (e.g. unsubstituted carbamoyl or diethylcarbamoyl), an acyl group (e.g. an acetyl group or a benzoyl group), an oxycarbonyl group (e.g. a methoxycarbonyl group or an ethoxycarbonyl group), a sulfonyl group (e.g. a methanesulfonyl group or a benzenesulfonyl group), a sulfonyloxy group (e.g. a methanesulfonyloxy group), a carbonyloxy group (e.g. an acetoxy group), a sulfamoyl group (e.g. an unsubstituted sulfamoyl group or a dimethylsulfamoyl group) and a heterocyclic group (e.g. a 2-thienyl group, a 2-benzoxazolyl group, a 2-benzothiazolyl group, a 1-methyl-2-benzimidazolyl group, a 1-tetrazolyl group or a 2-quinolyl group). Carbon-containing groups for R₂₁ preferably contain 1 to 20 carbon atoms.

Examples of the substitutable group represented by R₂₂ are those listed above as substituents for R.

It is preferable that a half or more of the R₂₂ groups contained in a compound represented by the formula (IV) are hydrogen atoms. R₂₂ groups present in a molecule may be the same or different.

R₂₁ and R₂₂ may be further substituted, and preferred examples of the substituents are those listed above as substituents for R.

Also, R₂₁ and R₂₂ or two or more R₂₂ groups may combine together to form a 3- to 6-membered ring.

A compound represented by formula (III) usable in the present invention is described below. Formula (III):

In the formula (III), R₃₁ represents an R₃₃O group, an R₃₃S group, an (R₃₃)₂N group, a (R₃₃)₂P group or phenyl, wherein R₃₃ represents a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an alkynyl group having 2 or 3 carbon atoms, an aryl group having 6 to 30 carbon atoms, an aralkyl group having 7 to 30 carbon atoms or a heterocyclic group having 4 to 30 carbon atoms. Each R₃₂ group represents a hydrogen atom or a substitutable group.

Groups each having the number of carbon atoms falling within this range are preferred in terms of their solubility and the amount in which they are used.

If R₃₁ represents a (R₃₃)₂N group or a (R₃₃)₂P group, the two R₃₃ groups may be the same or different. R₃₁ is preferably the R₃₃O group.

R₃₃ and n₃ have the same meanings as R₂₂ in the formula (II), and a plurality of R₃₃ groups may be the same or different. Examples of the substitutable group represented by R₃₃ are those enumerated above as substituents for R. R₃₃ is preferably a hydrogen atom.

n3 is preferably 1, 2, 4 or 5 and particularly preferably 2.

R₃₁ and R₃₃ may be further substituted. Preferred examples of the substituents are those listed above as substituents for R.

Also, R₃₁ and R₃₃ or two or more R₃₃ groups may bond together to form a ring.

Specific examples of the compounds represented by formulas (I), (II) and (III) usable in the present invention are described below, but the present invention is not limited to these examples.

The iodide ion releasing agent usable in the present invention can be synthesized according to the synthesis methods disclosed in J. Am. Chem. Soc., 76, 3227-8 (1954); J. Org. Chem., 16, 798 (1951), Chem. Ber., 97, 390 (1964), Org. Synth., V, 478 (1973), J. Chem. Soc. (1951), 1851, J. Org. Chem., 19, 1571 (1954), J. Chem. Soc. (1952), 142, J. Chem. Soc. (1955), 1383, Angew. Chem., Int. Ed., 11, 229 (1972), Chem. Commun. (1971), 1112.

The iodide ion releasing agent usable in the present invention releases iodide ions by reacting with an iodide ion release controlling agent (a base and/or a nucleophilic reagent). Preferred examples of the nucleophilic reagent for this purpose are the following chemical species:

Hydroxide ion, sulfite ion, hydroxylamine, thiosulfate ion, metabisulfite ion, hydroxamic acids, oximes, dihydroxybenzenes, mercaptans, sulfinate, carboxylate, ammonia, amines, alcohols, ureas, thioureas, phenols, hydrazines, hydrazides, semicarbazides, phosphines and sulfides.

In the present invention, the rate and time at which the iodide ion is released can be controlled by regulating the concentration of the base or nucleophilic reagent, the method of addition, or the temperature of the reaction solution. A preferred example of the base is alkali hydroxide.

The concentration range of the iodide ion releasing agent and the iodide ion release controlling agent for use in the rapid generation of iodide ions is preferably 1 x 10⁻⁷ to 20 M, particularly preferably 1 x 10⁻⁵ to 10 M, more preferably 1 x 10⁻⁴ to 5 M, and most preferably 1 x 10⁻³ to 2 M.

If the concentration exceeds 20 M, the total amount of the iodide ion releasing agent and the iodide ion release controlling agent, both of which have a large molecular weight, will be excessive for the volume of the grain forming vessel used. On the other hand, if the concentration is less than 1 x 10-7; M, the reaction rate of releasing iodide ions will be too low, making it difficult to generate iodide ions quickly.

The temperature range is preferably 30 to 80ºC, more preferably 35 to 75ºC and most preferably 35 to 60ºC.

In general, the reaction rate of release of iodide ions is too high at high temperatures above 80ºC and too low at low temperatures below 30ºC. The temperature range within which the iodide ion releasing agent should be used is therefore limited.

In the present invention, changes in the pH of the solution may be used if the base is used in the release of iodide ions.

In this case, the pH range for regulating the rate and time at which iodide ions are released is preferably 2 to 12, more preferably 3 to 11, and particularly preferably 5 to 10. The pH is most preferably 7.5 to 10.0 after regulation. The ion product of the water certain hydroxide ions act as regulating agents even under a neutral condition of pH 7.

It is also possible to use the nucleophilic reagent and the base together. In this case, the rate and time at which the iodide ions are released can also be controlled by regulating the pH within the above range.

The range of amounts of iodide ions released from the iodide ion releasing agent is preferably 0.1 to 20 mol%, more preferably 0.3 to 15 mol%, and most preferably 1 to 10 mol%.

The iodide ions can be released in any amount in the range of 0.1 to 20 mol% that is appropriate for the purpose for which the ions are used. However, if the amount exceeds 20 mol%, the development rate will decrease in most cases.

If iodine atoms are to be released in the form of iodide ions from the iodide ion-releasing agent, iodine atoms may either be completely released or partially remain undecomposed.

The rate at which iodide ions are released from the iodide ion releasing agent is described below by practical examples.

In the present invention, it is preferable to form a silver halide phase containing silver iodide on the edges of a tabular grain while rapidly generating iodide ions during the process of introducing dislocation lines into the tabular grain. to introduce dislocation lines with high density. If the supply rate of iodide ions is too low, that is, if the time required to form a silver halide phase containing silver iodide is too long, the silver halide phase containing silver iodide redissolves during formation and the dislocation line density decreases. On the other hand, the supply of iodide ions when carrying out grain formation is preferably low so that non-uniformity in the distribution of dislocation lines between individual grains is not generated.

It is therefore important that iodide ions are rapidly generated without causing locality (non-uniform distribution). When the iodide ion releasing agent or the iodide ion release controlling agent to be used together therewith is added through an inlet to a reaction solution charged in a grain forming vessel, a locality having a high concentration of the added agent can be formed near the inlet. Thus, a locality of generated iodide ions is accordingly produced because the iodide ion releasing reaction proceeds very rapidly.

The rate at which released iodide ions are deposited on a host grain is very high and grain growth occurs in an area near the feed inlet where the locality of iodide ions is high. The result is non-uniform grain growth between individual grains. Therefore, the iodide ion release rate must be selected so that it does not cause locality of iodide ions.

In conventional methods (e.g., in a method of adding an aqueous potassium iodide solution), the iodide ion is added in a free state even if an aqueous potassium iodide solution is diluted before addition. This limits the reduction of the locality of iodide ions. That is, it is difficult for the conventional methods to carry out grain formation without causing nonuniformity between grains. However, the present invention, which can regulate the iodide ion release rate, makes it possible to reduce the locality of iodide ions compared with the conventional methods. In the example described above, dislocation lines can be introduced in high density and uniformly between individual grains, compared with the conventional methods, by the use of the present invention, which can carry out grain formation while generating iodide ions quickly without causing locality.

In the present invention, the iodide ion release rate can be determined by regulating the temperature and concentrations of the iodide ion release agent and the iodide ion release controlling agent, and therefore can be selected according to the intended use.

In the present invention, the iodide ion releasing rate is such that 100 to 50% of the total weight of the iodide ion releasing agent present in the reaction solution in a grain forming vessel completes the release of iodide ions within 180 continuous seconds, preferably within 120 seconds, and particularly preferably within 60 seconds.

Preferably, the iodide ions should be released over at least one second.

The words "180 continuous seconds" mean a period of time for which the reaction of releasing iodide ions proceeds. The iodide ion releasing period may be measured starting at any time during the continuous reaction. If the iodide ions are released during two or more periods that are separated, the iodide ion releasing period may be measured starting at any time during the first period or another period. The ion release rate may be determined at any time during the first period or another period.

A release rate where the time exceeds 180 seconds is generally low, and a release rate where the time exceeds less than 1 second is generally low. The release rate is limited. This is similarly true of a release rate where the amount of iodide ion releasing agent is less than 50%.

A particularly preferred rate is that at which 100 to 70% of the iodide ion releasing agent present in the reaction solution in a grain forming vessel completes the release of iodide ions within 180 continuous seconds. The rate is more preferred that at which 100 to 80%, and most preferably 100 to 90%, completes the release of iodide ions within 180 continuous seconds.

"Completion of release of iodide ions" means that all of the iodine contained in a particular iodide ion-releasing agent is released from the releasing agent in the form of ions. For example, in the case of an iodide ion-releasing agent having one iodine atom in the molecule, release of iodide ions is complete when that one iodine atom is released from the releasing agent. In the case of an iodide ion-releasing agent having 2 or more iodine atoms in the molecule, release of iodide ions is complete when all of the 2 or more iodine atoms are released therefrom.

When the reaction of rapid generation of iodide ions is represented by a second order reaction which is substantially proportional to the concentration of the iodide ion releasing agent and that of the iodide ion release controlling agent (in water, 40°C), the rate constant of the second order reaction in the present invention is preferably 1,000 to 5 x 10-3 (M-1 s-1), more preferably 100 to 5 x 10-2 (M-1 s-1), and most preferably 10 to 0.1 (M-1 s-1).

The "substantially second order reaction" means that the correlation coefficient is 1.0 to 0.8. The following are representative examples of a second order reaction rate constant (k) (M⁻¹ s⁻¹) measured under the conditions considered as a pseudo-first order reaction - i.e., the concentration of the iodide ion releasing agent is in the range of 10⁻⁴ to 10⁻⁵ M, the concentration of the iodide ion release controlling agent is in the range of 10⁻¹ to 10⁻⁴ M, in water and at 40°C.

If (k) exceeds 1,000, the release is too fast to control; if it is less than 5 x 10³, the release is too slow to obtain the effect of the present invention.

The following method is preferred for regulating the release of iodide ions in the present invention.

That is, this method allows the iodide ion releasing agent, which is added to a reaction solution in a grain forming vessel and is already uniformly distributed, to release iodide ions uniformly in the reaction solution by changing the pH, the concentration of a nucleophilic substance or the temperature, usually by changing from a low to a high pH.

It is preferable that alkali and the nucleophilic substance used together with alkali for increasing pH during the release of iodide ions are added in a state in which the iodide ion-releasing agent is uniformly distributed in the reaction solution.

Specifically, in the present invention, iodide ions to be reacted with silver ions are rapidly generated in a reaction system to form silver halide grains containing silver iodide (e.g., silver iodide, silver bromoiodide, silver bromochloroiodide or silver chloroiodide). In most cases, the iodide ion-releasing agent usable in the present invention is added, if necessary, besides another halogen ion source (e.g., KBr), to the reaction system using as a reaction medium an aqueous gelatin solution containing silver ions due to the addition of, for example, silver nitrate or containing silver halide grains (e.g., silver bromoiodide grains), and the iodide ion-releasing agent is uniformly distributed in the reaction system by a known method (such as stirring). In this step, the reaction system has a low pH and is weakly acidic, and the iodide ion-releasing agent does not release iodide ions rapidly.

An alkali (e.g., sodium hydroxide or sodium sulfite) is then added to the reaction system as an iodide ion release controlling agent, thereby raising the pH of the system to the alkaline range (preferably to 7.5 to 10). As a result, iodide ions are rapidly released from the iodide ion releasing agent. The iodide ions react with the silver ions or undergo halogen conversion with the silver halide grains, thereby forming a silver iodide-containing region.

As indicated, the reaction temperature is usually in the range of 30 to 80°C, more preferably 35 to 75°C, and most preferably 35 to 60°C. The iodide ion releasing agent usually releases iodide ions at a rate such that 100 to 50% of the By means of completing the release of iodide ions within a continuous period of 1 to 180 seconds starting from the time of addition of the alkali. Which iodide ion releasing agent and which iodide ion release controlling agent should be used in combination and in what amounts they should be used to cause the iodide ion releasing agent to release iodide ions at such a rate is determined according to the second order reaction rate constant described above.

In order to distribute the alkali uniformly in the reaction system (i.e., to produce silver iodide uniformly), it is desirable that the alkali be added while the reaction system is vigorously stirred by, for example, a controlled double-jet method.

The emulsion grain usable in the present invention is described below.

The emulsion grain usable in the present invention is a silver halide containing silver iodide.

The emulsion grain usable in the present invention contains at least one of a silver iodide phase, a silver bromoiodide phase, a silver bromochloroiodide phase and a silver iodochloride phase. The emulsion grain may also contain another silver salt, e.g., silver rhodanide, silver sulfide, silver selenide, silver carbonate, silver phosphate and a silver salt of an organic acid, as another grain or as part of the silver halide grain.

The range of silver iodide content of the emulsion grain usable in the present invention is preferably 0.1 to 20 mol%, more preferably 0.3 to 15 mol%, and most preferably 1 to 10 mol%.

The silver iodide content can be released in any amount in the range of 0.1 to 20 mol% that is suitable for the purpose for which the ions are used. However, if the amount exceeds 20 mol%, the development rate will decrease in most cases.

The effect of the present invention will be outstanding if use is made of silver halide grains of regular crystal whose crystal phase and shape are specific and which are uniform in properties. In the case of regular crystal, it is possible to use a cubic grain represented by (100) faces, an octahedral grain represented by (111) faces, or a dodecahedral grain represented by (110) faces disclosed in JP-B-55-42737 or JP-A-60-222842. It is also possible, according to the intended use of an emulsion, to use a (h11) face grain represented by a (211) face, a (hhl) face grain represented by a (331) face, a (hk0) face grain represented by a (210) face, or a (hk1) face grain represented by a (321) face, as reported in Journal of Imaging Science, Vol. 30, page 247, 1986, although the manufacturing process requires some improvements. A grain having two or more different faces, such as a tetradecahedral grain having both (110) faces and (111) faces, a grain having (100) faces and (110) faces, or a grain having (111) faces and (110) faces can also be used according to the intended use of an emulsion.

In the present invention, it is preferable that 60% or more of the surface of each regular crystal grain is a (111) face or a (100) face. When regular crystal grains of such a type were used, the advantages of the invention were outstanding.

The percentage of (111) area or (100) area is determined by the method disclosed in T. Tani, Journal of Imaging Science 29, 165 (1985).

Regular crystal grains of which 60% or more of the surface is either the (111) face or (100) face can be obtained by forming grains by a regulated double jet method, i.e., one of the simultaneous mixing methods in which the pAg in the liquid phase of silver halide is kept at a constant value by using an appropriate electric control potential.

The emulsion grain usable in the present invention preferably has one of the following structures based on the halogen composition.

(1) A grain with one or more cover shells on a substrate grain:

It is preferable to form the core or the outermost shell of a double structure, triple structure, quadruple structure, quintuple structure, ..., or multiple structure by using the iodide ion release method usable in the present invention.

(2) A grain in which one or more layers, which do not completely cover a substrate grain, are deposited on the substrate grain:

It is preferable to form the core layer or the outermost layer of a two-layer structure, three-layer structure, four-layer structure, five-layer structure, ..., or multi-layer structure by using the iodide ion releasing method usable in the present invention.

(3) A grain in which epitaxial growth is carried out on selected regions of a substrate grain :

It is preferable to form the epitaxial regions on the corners, the edges and the major faces of a grain by using the iodide ion release method usable in the present invention.

It is preferred that the compositions of the cover shells, the deposited layers and the epitaxial regions of a silver iodide-containing silver halide formed by using the iodide ion release process useful in the present invention have high silver iodide contents.

Although these silver halide phases may be any of silver iodide, silver bromoiodide, silver bromochloroiodide and silver iodochloride, they are preferably silver iodide or silver bromoiodide and particularly preferably silver iodide.

When the silver halide phase is silver bromoiodide, the silver iodide (iodide ion) content is preferably 1 to 45 mol%, more preferably 5 to 45 mol%, and most preferably 10 to 45 mol%.

If the silver iodide content is less than 1 mol%, dye adsorption will not be sufficiently increased, intrinsic sensitivity will not be sufficiently improved, and defects required for the introduction of dislocation lines will not be formed. If the content exceeds 45 mol%, silver iodide can no longer be a solid solubility limitation.

It is preferable to produce silver halide grains containing dislocation lines by using the iodide ion release method usable in the present invention.

A dislocation line is a linear lattice defect at the boundary between an already displaced area and an not yet displaced area on a slip plane of the crystal.

Dislocation lines in silver halide crystals are described, for example, in (I) C. R. Berry, J. Appl. Phys., 27, 636 (1956), (2) C. R. Berry, D. C. Skilman, J. Appl. Phys., 35, 2165 (1964), (3) J. F. Hamilton, Phot. Sci. Eng., 11, 57 (1967), (4) T. Shiozawa, J. Soc. Sci. Jap., 34, 16 (1971) and (5) T. Shiozawa, J. Soc. Phot. Sci. Jap., 35, 213 (1972). Dislocation lines can be analyzed by an X-ray diffraction method or a direct observation method using a low-temperature transmission electron microscope.

In direct observation of dislocation lines using a transmission electron microscope, silver halide grains, carefully taken out of an emulsion so that no pressure is applied that creates dislocation lines in the grains, are placed on a grid designed for use in electron microscope observation and cooled to avoid damage (e.g. imprint) due to electron beams. Then, observation of the sample is carried out by a transmission method.

In this case, as the thickness of a grain increases, it becomes more difficult to pass electron beams through it. Therefore, grains can be observed more clearly using a high-voltage type electron microscope (200 kV or more for a thickness of 0.25 µm).

The effects that dislocation lines have on photographic properties are described in G. C. Farnell, R. B. Flint, J. B. Chanter, J. Phot. Sci., 13, 25 (1965). This reference shows that in large size, high aspect ratio tabular silver halide grains, the location at which a latent image spot is formed has a close relationship to a defect in the grain.

JP-A-63-220238 and JP-A-1-201649 disclose tabular silver halide grains into which dislocation lines are intentionally introduced.

These patent applications state that tabular grains into which dislocation lines are introduced are superior to those without dislocation lines in the photographic properties how sensitivity and reciprocity law are superior.

A method for introducing dislocation lines into a silver halide grain is described.

In the present invention, it is preferable to introduce dislocation lines into a silver halide grain as follows.

That is, after producing silver halide grains serving as substrate grains, silver iodide-containing silver halide phases (silver halide as a cover shell, deposited layers and epitaxial growth as described above) are formed on these substrate grains.

As mentioned above, it is preferred that the silver iodide contents of these silver halide phases be as high as possible.

The silver iodide content of the substrate grain is preferably 0 to 15 mol%, more preferably 0 to 12 mol%, and most preferably 0 to 10 mol%.

If the silver iodide content exceeds 15 mol%, the development speed will decrease in most cases. The silver iodide content is selected according to the purpose for which the emulsion is used.

An amount of halogen to be added to form this high silver iodide phase on the substrate grain is preferably 2 to 15 mol%, more preferably 2 to 10 mol%, and most preferably 2 to 5 mol%, with respect to the silver amount of the substrate grain.

If the halogen content is less than 2 mol%, dislocation lines cannot be easily introduced into the grains. If the halogen content exceeds 15 mol%, the development rate will decrease. The halogen content is selected according to the purpose for which the emulsion is used.

The high silver iodide phase falls within a range of preferably 5 to 80 mol%, more preferably 10 to 70 mol%, and most preferably 20 to 60 mol% with respect to the silver amount of the total grain.

If the high silver iodide phase is less than 5 mol% or exceeds 80 mol%, dislocation lines cannot be easily introduced into the grains to increase the sensitivity of the emulsion.

The location on the substrate grain where the high silver iodide phase is to be formed can be selected as desired. Although the high silver iodide phase can be formed to cover the substrate grain or in a particular region, it is preferable to control the positions of the dislocation lines within a grain by epitaxially growing the phase at a specific selected region.

In this case, it is possible to freely select the composition of the halogen to be added, the addition method, the temperature of the reaction solution, the pAg, the solvent concentration, the gelatin concentration and the ionic strength.

Dislocation lines can then be introduced by forming a silver halide shell outside the phases.

The composition of this silver halide shell can be any of silver bromide, silver bromoiodide and silver bromochloroiodide, but is preferably silver bromide or silver bromoiodide.

When the silver halide shell consists of silver bromoiodide, the silver iodide content is preferably 0.1 to 12 mol%, more preferably 0.1 to 10 mol%, and most preferably 0.1 to 3 mol%.

If the silver iodide content is less than 0.1 mol%, dye adsorption will not be sufficiently increased and development will not be sufficiently promoted. If the content exceeds 12 mol%, the development speed will decrease.

In the above method of introducing dislocation lines, the temperature is preferably 30 to 80°C, more preferably 35 to 75°C, and most preferably 35 to 60°C.

If the temperature is lower than 30ºC or higher than 80ºC, it is difficult to control in the apparatus used in most cases. To control the temperature outside the range of 30 to 80ºC, it would be necessary to use an apparatus with greater capabilities, which is undesirable in terms of manufacturing costs.

A preferred pAg is 6.4 to 10.5.

In the cases of regular crystal grains, the positions and number of dislocation lines of individual grains, viewed in a direction perpendicular to their major faces, can also be obtained from a photograph of the grains taken by using an electron microscope.

It is noted that dislocation lines may or may not be detected depending on the inclination angle of the sample with respect to the electron beams. Therefore, in order to observe dislocation lines without omission, it is necessary to obtain the positions of the dislocation lines by observing photographs of the same grain taken at as many sample inclination angles as possible.

In the present invention, it is preferable to take 5 photographs of the same grain at 5°-step different inclination angles by using a high-voltage electron microscope, thereby determining the positions and number of dislocation lines.

It is desirable that dislocation lines are introduced into a grain with regular crystal.

Each regular crystal grain preferably has 10 or more, more preferably 30 or more, and most preferably 50 or more dislocation lines when the dislocation lines are counted by the method described above using an electron microscope.

If dislocation lines are densely present or cross each other, it is sometimes impossible to accurately count the dislocation lines per grain.

However, even in this case, dislocation lines can be counted roughly in such a way as in units of ten, such as 10, 20 and 30.

It is desirable that the quantity distribution of dislocation lines between individual grains with regular crystal is uniform.

In the present invention, when dislocation lines are to be introduced into grains having regular crystal, the grains each having 10 or more dislocation lines in their edge region preferably occupy 100 to 50% (number), more preferably 100 to 70%, and most preferably 100 to 90% of all grains.

If such tabular grains occupy less than 50% of all grains, the grains will not have the desired uniformity.

In the present invention, in order to obtain the ratio of grains containing dislocation lines and the number of dislocation lines, it is preferable to directly observe dislocation lines for at least 100 grains, more preferably for 200 grains or more, and most preferably 300 grains or more.

It is preferable to form the outermost shell near the surface of a silver halide grain by using the iodide ion releasing method usable in the present invention.

The formation of a silver halide phase containing silver iodide near the surface of a grain is important in increasing the dye absorption power and controlling the development rate.

In the present invention, the "surface of a grain" means a region with a depth of about 50 Å from the surface of a grain.

The halogen composition in such a region can be measured by a surface analysis technique such as XPS (X-ray photoelectron spectroscopy) or ISS (ion scattering spectroscopy).

In the present invention, the silver iodide content of a silver halide phase formed on the surface of an emulsion grain, measured by these surface analysis methods, is preferably 0.1 to 15 mol%, more preferably 0.3 to 12 mol%, particularly preferably 1 to 10 mol%, and most preferably 3 to 8 mol%.

If the silver iodide content is less than 0.1 mol%, dye adsorption will not be sufficiently increased and development will not be sufficiently promoted. If the content exceeds 15 mol%, the development speed will decrease.

It is also desirable that the halogen compositions of the whole grains be uniform between individual grains.

In the present invention, the coefficient of variation of the distribution of silver iodide contents between individual emulsion grains preferably 20% or less, more preferably 15% or less, most preferably 10% or less, and preferably 3% or more.

If the coefficient of variation of the silver iodide content distribution exceeds 20%, the uniformity among grains will be deteriorated.

The silver iodide contents of individual emulsion grains can be measured by analyzing the composition of each grain using an X-ray microanalyzer.

The coefficient of variation of a silver iodide content distribution is the value obtained by dividing the variation (standard deviation) of the silver iodide contents of individual grains by the average silver iodide content.

A silver halide emulsion used in the present invention may be subjected to a grain rounding treatment as disclosed in EP-B1-96 727 or EP-B1-64 412 or a surface modification as disclosed in DE-PS-23 06 447 or JP-A-60 221320.

Although a flat grain surface is common, an intentional concavo-convex formation on the surface is preferred in some cases. Examples are the methods described in JP-A-58-106532 and JP-A-60-221320 in which a hole is formed in a part of a crystal, e.g., the corner or the center of the face of a crystal, and a ripple grain described in U.S. Patent No. 643,966.

The grain size of an emulsion used in the present invention can be evaluated in terms of the equivalent circle diameter of the projected area of a grain obtained using an electron microscope, the equivalent sphere diameter of the volume of a grain calculated from the projected area and the diameter of the grain, or the equivalent sphere diameter of the volume of a grain obtained by a Coulter counter method. It is possible to selectively use various grains from a very fine grain having an equivalent sphere diameter of 0.05 µm or less to a large grain having one of 10 µm or more. It is preferable to use a grain having an equivalent sphere diameter of 0.1 to 3 µm as the light-sensitive silver halide grain.

For regular crystal emulsions, it is possible to use a so-called polydisperse emulsion having a broad grain size distribution or a monodisperse emulsion having a narrow grain size distribution according to the intended use. As a measure representing the size distribution, the coefficient of variation of either the equivalent circle diameter of the projected area of a grain or the equivalent sphere diameter of the volume of a grain is sometimes used. When a monodisperse emulsion is to be used, it is desirable to use an emulsion having a size distribution with a coefficient of variation of preferably 25% or less, more preferably 20% or less, and most preferably 15% or less.

The monodisperse emulsion is sometimes defined as an emulsion with a particle size distribution in which 80% or more of all grains fall within a range of + 30% of the average grain size represented by the number or weight of the grains. In order for a light-sensitive material to satisfy its target gradation, two or more monodisperse silver halide emulsions having different grain sizes may be mixed in the same emulsion layer or coated as different layers in an emulsion layer having substantially the same color sensitivity. It is also possible to mix two or more types of polydisperse silver halide emulsions or monodisperse emulsions together with polydisperse emulsions or to coat them as different layers.

Photographic emulsions used in the present invention and other photographic emulsions used together with the photographic emulsions of the present invention can be prepared by the methods described, for example, in P. Glafkides, Chimie et Physique Photographique, Paul Montel, 1967; GF Duffin, Photographic Emulsion Chemistry, Focal Press 1966; and VL Zelikman et al., Making and Coating Photographic Emulsion, Focal Press, 1964. That is, any one of an acid method, a neutral method and an ammonia method can be used. In forming grains by reacting a soluble silver salt and a soluble halogen salt, any one of a single jet method, a double jet method and a combination of these methods can be used. It is also possible to use a method (so-called reverse double jet method) of forming grains in the presence of excess silver ions. As one type of double jet method, a method can be used in which the pAg of the liquid phase is production of a silver halide is kept constant, ie a so-called controlled double jet process. This process makes it possible to obtain a silver halide emulsion in which the crystal shape is regular and the grain size is almost uniform.

In some cases, it is preferable to use a method of adding silver halide grains already formed by precipitation into a reactor vessel for emulsion preparation, and the methods described in U.S. Patents 4,334,012, 4,301,241 and 4,150,994. These silver halide grains can be used as seed crystals and are also effective when provided as silver halide for growth. In the latter case, the addition of an emulsion having a small grain size is preferable. The entire amount of an emulsion may be added at once, or an emulsion may be added separately several times or continuously. In addition, it is sometimes effective to add grains having various different halogen compositions to modify the surface.

A method for converting most or only a part of the halogen composition of a silver halide grain by a halogen conversion method is disclosed, for example, in US Patents 3,477,852 and 4,142,900, EP-B-273,429 and EP-B-273,430 and DE-OS-38 19 241. This method is an effective grain forming method. For conversion to a silver salt which can hardly be dissolved, it is possible to add a solution of a soluble halogen salt or silver halide grains. The conversion can once, separately several times or continuously.

As a grain growth method other than the method of adding a soluble silver salt and a halogen salt at a constant concentration and a constant flow rate, it is preferable to use a grain formation method in which the concentration or the flow rate is changed, as described in British Patent No. 1,469,480 and US Patent Nos. 3,650,757 and 4,242,445. The increase in the concentration or the flow rate can change the amount of silver halide to be added as a linear function, quadratic function or more complex function of the addition time. It is also preferable to decrease the amount of silver halide to be added if necessary depending on the situation. Furthermore, when a plurality of soluble silver salts of different solution compositions are to be added, or a plurality of soluble halogen salts of different solution compositions are to be added, a method of increasing one of the salts while decreasing the other is also effective.

A mixing vessel for reacting solutions of soluble silver salts and soluble halogen salts can be selected from those described in US Patents 2,996,287, 3,342,605, 3,415,650 and 3,785,777 and DE-OS-25 56 885 and DE-OS-25 55 364.

A silver halide solvent is useful for the purpose of accelerating ripening. For example, it is known to introduce an excess of halogen ions into a reactor vessel to accelerate ripening.

Another ripening agent may also be used. The total amount of these ripening agents may be mixed in a dispersing medium added to the reactor vessel prior to the addition of silver and halide salt, or may be introduced into the reactor vessel simultaneously with the addition of halide salt, silver salt or floc destroyer. Alternatively, ripening agents may be added independently at the stage of adding a halide salt and a silver salt.

Examples of the ripening agent are ammonia, thiocyanate (e.g. potassium thiocyanate and ammonium thiocyanate), an organic thioether compound (e.g. a compound described in U.S. Patents 3,574,628, 3,021,215, 3,057,724, 3,038,805, 4,276,374, 4,297,439, 3,704,130 or 4,782,013 and JP-A-57-104926), a thione compound (e.g. a tetrasubstituted thiourea described in JP-A-53-82408, JP-A-55-77737 or U.S. Patent 4,221,863 or a compound described in JP-A-53-144319) mercapto compounds capable of accelerating the growth of silver halide grains described in JP-A-57-202531, and an amine compound (e.g. JP-A-54-100717).

It is advantageous to use gelatin as a protective colloid for use in the preparation of emulsions in the present invention or as a binder for other hydrophilic colloid layers. However, another hydrophilic colloid may also be used instead of gelatin.

Examples of the hydrophilic colloid are proteins such as a gelatin derivative, a graft polymer of gelatin and another high polymer, albumin and casein; a Cellulose derivatives such as hydroxyethylcellulose, carboxymethylcellulose and cellulose sulfates; sugar derivatives such as sodium alginate and a starch derivative; and a variety of synthetic hydrophilic high polymers such as homopolymers or copolymers, e.g. polyvinyl alcohol, polyvinyl alcohol hemiacetal, poly-N-vinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinylimidazole and polyvinylpyrazole.

Examples of gelatin are lime-treated gelatin, acid-treated gelatin and enzyme-treated gelatin, described in Bull. Soc. Sci. Photo. Japan, No. 16, page 30 (1966). In addition, a hydrolyzed product or an enzyme-degraded product of gelatin can also be used.

It is preferable to wash an emulsion in the present invention for the purpose of desalting and disperse it in a freshly prepared protective colloid dispersion. Although the temperature of washing can be selected according to the intended use, it is preferably 5 to 50°C. Although the pH in washing can also be selected according to the intended use, it is preferably 2 to 10, and particularly preferably 3 to 8. The pAg in washing is preferably 5 to 10, although it can also be selected according to the intended use. The washing method can be selected from noodle washing, dialysis using a semipermeable membrane, centrifugal separation, coagulation precipitation and ion exchange. The coagulation precipitation can be selected from a method using sulfate, a method using an organic solvent, a method using a water-soluble polymer and a Process using a gelatin derivative can be selected.

In preparing an emulsion of the present invention, it is preferable to provide a salt of a metal ion during grain formation, desalting or chemical sensitization or before coating according to the intended use. The metal ion salt is preferably added during grain formation when carrying out doping for the grains and after grain formation and before completion of chemical sensitization when modifying the grain surface or when used as a chemical sensitizer. Doping may be carried out for each of a whole grain, only the core, shell or epitaxial region of a grain and only a substrate grain. Examples of the metal are Mg, Ca, Sr, Ba, Al, Sc, Y, La, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ru, Rh, Pd, Re, Os, Ir, Pt, Au, Cd, Hg, Tl, In, Sn, Pb and Bi. These metals can be added as long as they are in the form of a salt that can be dissolved during grain formation, such as ammonium salt, acetate, nitrate, sulfate, phosphate, hydroxide, 6-coordinate complex salt or 4-coordinate complex salt. Examples are CdBr2, CdCl2, Cd(NO3)2, Pb(NO3)2, Pb(CH3COO)2, K3[Fe(CN)6], (NH4)4[Fe(CN)6], K3IrCl6, (NH4)3RhCl6 and K4Ru(CN)6. The ligand of a coordination compound can be selected from halogeno, aquo, cyano, cyanate, thiocyanate, nitrosyl, thionitrosyl, oxo and carbonyl. These metal compounds can be used either singly or in a combination of two or more types thereof.

The metal compounds are preferably dissolved in water or a suitable organic solvent such as methanol or acetone and added in the form of a solution. To stabilize the solution, an aqueous hydrogen halide solution (e.g. HCl and HBr) or an alkali halide (e.g. KCl, NaCl, KBr and NaBr) may be added. It is also possible to add acid or alkali if required. The metal compounds can be added to the reactor vessel either before or during grain formation. Alternatively, the metal compounds can be added to a water-soluble silver salt (e.g. AgNO3) or an aqueous alkali halide solution (e.g. NaCl, KBr and KI) and added in the form of a solution continuously during the formation of silver halide grains. In addition, a solution of the metal compounds can be prepared independently of a water-soluble salt or an alkali halide and added continuously at an appropriate time during grain formation. It is also possible to combine several different addition methods.

It is sometimes useful to carry out a process of adding a chalcogen compound during the preparation of an emulsion as described in U.S. Patent No. 3,772,031. In addition to S, Se and Te, cyanate, thiocyanate, selenocyanic acid, carbonate, phosphate and acetate may be present.

In the formation of silver halide grains in the present invention, at least one of sulfur sensitization, selenium sensitization, gold sensitization, palladium sensitization or noble metal sensitization and reduction sensitization may be carried out at any point during the process for preparing a silver halide emulsion. The use of two or more different sensitization methods is preferred. Several different types of emulsions can be prepared by changing the timing at which chemical sensitization is carried out. The types of emulsions are classified into: a type in which a chemical sensitization spot is embedded in a grain, a type in which it is embedded at a shallow position from the surface of the grain, and a type in which it is formed on the surface of a grain. In the emulsions usable in the present invention, the location of the chemical sensitization spot can be selected according to the intended use. However, it is generally preferred to form at least one type of chemical sensitization spot near the surface.

A chemical sensitization that can preferably be carried out in the present invention is chalcogen sensitization, noble metal sensitization or a combination of these. Sensitization can be carried out using active gelatin as described in TH James, The Theory of the Photographic Process, 4th ed., Macmillan, 1977, pages 67 to 76. Sensitization can also be carried out using a member of sulfur, selenium, tellurium, gold, platinum, palladium and iridium or by using a combination of a plurality of these sensitizers at pAg 5 to 10, pH 5 to 8 and a temperature of 30 to 80°C as described in Research Disclosure, Vol. 120, April 1974, 12008, Research Disclosure, Vol. 34, June 1975, 13452, U.S. Patents 2,642,361, 3,297,446, 3,772,031, 3,857,711, 3 901 714, 4 266 018 and 3 904 415 and GB-PS 1 315 755. In precious metal sensitization, salts of precious metals such as gold, platinum, palladium and iridium. In particular, gold sensitization, palladium sensitization or a combination of both is preferred. In gold sensitization, it is possible to use known compounds such as chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide and gold selenide. A palladium compound means a divalent or tetravalent palladium salt. A preferred palladium compound is represented by R₂PdX₆ or R₂PdX₄, wherein R represents a hydrogen atom, an alkali metal atom or an ammonium group and X represents a halogen atom, ie, a chlorine, bromine or iodine atom.

More specifically, the palladium compound is preferably K₂PdCl₄, (NH₄)₂PdCl₆, Na₂PdCl₄, (NH₄)₂PdCl₄, Li₂PdCl₄, Na₂PdCl₆, or K₂PdBr₄. It is preferable that the gold compound and the palladium compound are used in combination with thiocyanate salt or selenocyanate salt.

Examples of a sulfur sensitizer are Hypo, a thiourea-based compound, a rhodanine-based compound, and sulfur-containing compounds described in U.S. Patent Nos. 3,857,711, 4,266,018, and 4,054,457.

It is preferable to also carry out gold sensitization for emulsions in the present invention. The amount of a gold sensitizer is preferably 1 x 10-4 to 1 x 10-7 mol, and particularly preferably 1 x 10-5 to 5 x 10-7 mol, per mol of silver halide. The preferable amount of a palladium compound is 1 x 10-3 to 5 x 10-7 mol per mol of silver halide. The preferable amount of a thiocyanate compound or a selenocyanate compound is 5 x 10-2 to 1 x 10-6 mol per mol of silver halide.

The amount of a sulfur sensitizer with respect to the silver halide grains in the present invention is preferably 1 x 10-4 to 1 x 10-7 mol, and particularly preferably 1 x 10-5 to 5 x 10-7 mol, per mol of silver halide.

Selenium sensitization is a preferred sensitization method for emulsions in the present invention. Known unstable selenium compounds are used in selenium sensitization. Practical examples of the selenium compound are colloidal metallic selenium, selenoureas (e.g., N,N-dimethylselenourea and N,N-diethylselenourea), selenoketones, and selenoamides. In some cases, it is preferable to carry out selenium sensitization in combination with one or both of sulfur sensitization and noble metal sensitization.

Chemical sensitization can also be carried out in the presence of a so-called chemical sensitization aid. Examples of a useful chemical sensitization aid are compounds such as azaindene, azapyridazine and azapyrimidine, which are known as compounds capable of suppressing fog and increasing sensitivity in the chemical sensitization process. Examples of the chemical sensitization aid and the modifier are described in U.S. Patent Nos. 2,131,038, 3,411,914 and 3,554,757, JP-A-58-126526 and G. F. Duffin, Photographic Emulsion Chemistry, pages 138 to 143.

Silver halide emulsions in the present invention are preferably subjected to reduction sensitization during grain formation, after grain formation and before or during chemical sensitization or after chemical sensitization.

The reduction sensitization can be selected from a method of adding reduction sensitizers to a silver halide emulsion, a method called silver ripening in which grains are grown or ripened in a low-pAg environment at pAg 1 to 7, and a method called high-pH ripening in which grains are grown or ripened in a high-pH environment at pH 8 to 11. It is also possible to carry out two or more of these methods together.

The method of adding reduction sensitizers is preferred in that the degree of reduction sensitization can be precisely adjusted.

Known examples of the reduction sensitizer are stannous chloride, ascorbic acid and its derivatives, amines and polyamines, a hydrazine derivative, formamidine sulfinic acid, a silane compound and a borane compound. In the reduction sensitization usable in the present invention, it is possible to selectively use these known reduction sensitizers or to use two or more types of compounds together. Preferred compounds as the reduction sensitizer are stannous chloride, thiourea dioxide, dimethylamine borane and ascorbic acid and its derivative. Although the addition amount of the reduction sensitizers must be selected to satisfy the emulsion preparation conditions, a preferred amount is 10-7 to 10-3 mol per mol of silver halide.

The reduction sensitizers are dissolved in water or an organic solvent such as alcohols, glycols, ketones, esters or amides, and the resulting solution is added during grain growth. Although addition to the reactor vessel in advance is also preferred, addition at a given time during grain growth is particularly preferred. It is also possible to add the reduction sensitizers to an aqueous solution of a water-soluble silver salt or a water-soluble alkali halide to precipitate silver halide grains using this aqueous solution. Alternatively, a solution of the reduction sensitizers may be added separately several times or continuously over a long period of time during grain growth.

It is preferable to use an oxidizing agent for silver during the process of preparing emulsions in the present invention. The oxidizing agent for silver means a compound having the action of converting metallic silver to silver ions. A particularly effective compound is that which converts very fine silver grains, such as a by-product in the process of forming silver halide grains and chemical sensitization, to silver ions. The silver ions thus produced may form a silver salt sparingly soluble in water, such as silver halide, silver sulfide or silver selenide, or a silver salt readily soluble in water, such as silver nitrate. The oxidizing agent for silver may be either an inorganic or organic substance. Examples of the inorganic oxidizing agent are ozone, hydrogen peroxide and its adducts (e.g. NaBO₂·H₂O₂·3H₂O, ₂NaCO₃·3H₂O₂, Na₄P₂O�7·2H₂O₂ and 2Na₂SO₄·H₂O₂·2H₂O), peroxyacid salts (e.g. K₂S₂O�8, K₂C₂O₆ and K₂P₂O₈), a peroxy complex compound (e.g. K₂[Ti(O₂)C₂O₄]·3H₂O, 4K₂SO₄·Ti(O₂)OHSO·2H₂O and Na₃[VO(O₂)(C₂H₄)₂·6H₂O), permanganate (e.g. KMnO₄), an oxyacid salt such as chromate (e.g. K₂Cr₂Or₇), a halogen element such as iodine and bromine, perhalate (e.g. potassium periodate), a salt of a high valence metal (e.g. potassium hexacyanoferrate(II)) and thiosulfonate.

Examples of the organic oxidizing agent are quinones such as p-quinone, an organic peroxide such as peracetic acid and perbenzoic acid, and a compound that releases active halogen (e.g. N-bromosuccinimide, chloramine T and chloramine B).

Preferred oxidizing agents usable in the present invention are an organic oxidizing agent such as ozone, hydrogen peroxide and its adducts, a halogen element or thiosulfonate salt, and an organic oxidizing agent such as the quinones. A combination of the above-described reduction sensitization and the oxidizing agent for silver is preferred. In this case, the reduction sensitization may be carried out after the oxidizing agent is used, or vice versa, or the reduction sensitization and the use of the oxidizing agent may be carried out simultaneously. These processes may be carried out during grain formation or chemical sensitization.

Photographic emulsions used in the present invention may contain various compounds to prevent fogging during the manufacturing process, storage or photographic processing of a light-sensitive material or to to stabilize photographic properties. Useful compounds are those known as antifoggants or stabilizers, e.g. thiazoles such as benzothiazolium salt, nitroimidazoles, nitrobenzimidazoles, chlorobenzimidazoles, bromobenzimidazoles, mercaptothiazoles, mercaptobenzothiazoles, mercaptobenzimidazoles, mercaptothiadiazoles, aminotriazoles, benzotriazoles, nitrobenzotriazoles and mercaptotetrazoles (especially 1-phenyl-5-mercaptotetrazole); mercaptopyrimidines; mercaptotriazines; a thioketo compound such as oxadolinethione; azaindenes such as triazaindenes, tetraazaindenes (especially hydroxy-substituted (1,3,3a,7)-tetraazaindenes) and pentaazaindenes. For example, the compounds described in U.S. Patents 3,954,474 and 3,982,947 and JP-B-52-28660 can be used. A preferred compound is described in JP-A-63-212932. Antifoggants and stabilizers can be added at any of various different times such as before, during and after grain formation, during water washing, during dispersion after washing, before, during and after chemical sensitization and before coating, according to the intended application. The antifoggants and stabilizers can be added during preparation of an emulsion to achieve their original antifogging effect and stabilizing effect. In addition, the antifoggants and stabilizers can be used for various purposes such as controlling the crystal habit of grains, reducing the grain size, reducing the solubility of grains, controlling chemical sensitization and controlling the arrangement of dyes.

Photographic emulsions used in the present invention are preferably subjected to spectral sensitization by methine dyes and the like to achieve the effects of the present invention. Useful dyes include a cyanine dye, a merocyanine dye, a composite cyanine dye, a composite merocyanine dye, a holopolar cyanine dye, a hemicyanine dye, a styryl dye and a hemioxonol dye. The most useful dyes are those belonging to a cyanine dye, a merocyanine dye and a composite merocyanine dye. Any nucleus commonly used as a basic heterocyclic nucleus in cyanine dyes can be contained in these dyes. Examples of a nucleus are a pyrroline nucleus, an oxazoline nucleus, a thiazoline nucleus, a pyrrole nucleus, an oxazole nucleus, a thiazole nucleus, a selenazole nucleus, an imidazole nucleus, a tetrazole nucleus and a pyridine nucleus; a nucleus in which an aliphatic hydrocarbon ring is condensed to any of the above nuclei; and a nucleus in which an aromatic hydrocarbon ring is condensed to any of the above nuclei, e.g., an indolenine nucleus, a benzindolenine nucleus, an indole nucleus, a benzoxazole nucleus, a naphthoxazole nucleus, a benzthiazole nucleus, a naphthothiazole nucleus, a benzoselenazole nucleus, a benzimidazole nucleus, and a quinoline nucleus. These nuclei may have a substituent on a carbon atom.

It is possible for a merocyanine dye or a compound merocyanine dye to have a 5- or 6-membered heterocyclic nucleus as a nucleus with a ketomethylene structure. Examples are a pyrazolin-5-one nucleus, a thiohydantoin nucleus, a 2-thiooxazolidine-2,4-dione nucleus, a thiazolidine-2,4-dione nucleus, a rhodanine nucleus and a thiobarbituric acid nucleus.

Although these sensitizing dyes can be used individually, they can also be used together. The combination of sensitizing dyes is often used for a hypersensitization purpose. Representative examples of the combination are given in US Patents 2,688,545, 2,977,229, 3,397,060, 3,522,052, 3,527,641, 3,617,293, 3,628,964, 3,666,480, 3,672,898, 3,679,428, 3,703,377, 3,769,301, 3,814,609, 3,837,862 and 4,026,707, UK Patents 1,344,281 and 1,507,803, JP-B-43-4936, JP-B-53-12375, JP-A-52-110618 and JP-A-52-109925.

In addition to the sensitizing dyes, emulsions may contain dyes without spectral sensitizing effect or substances that do not absorb substantially in visible light and cause hypersensitization.

The sensitizing dyes can be added to an emulsion at any point in the preparation of an emulsion which is conventionally known to be useful. Most usually, the addition is carried out after the completion of chemical sensitization and before coating. However, it is possible to carry out the addition at the same time as the addition of the chemical sensitizing dyes to carry out spectral sensitization and chemical sensitization simultaneously, as described in U.S. Patent Nos. 3,628,969 and 4,225,666. It is also possible to carry out the addition before chemical sensitization, as described in JP-A-58-113928, or before the completion of the formation of a silver halide grain precipitate to start spectral sensitization. Alternatively, these compounds described above can be added separately as disclosed in U.S. Patent No. 4,225,666; a portion of the compounds may be added before chemical sensitization, while the remaining portion is added afterward. That is, the compounds may be added at any time during the formation of silver halide grains, including by the method disclosed in U.S. Patent No. 4,183,756.

The addition amount of the spectral sensitizing dye may be 4 x 10⁻⁶ to 8 x 10⁻³ mol per mol of silver halide. However, for a particularly preferred silver halide grain size of 0.2 to 1.2 µm, an addition amount of about 5 x 10⁻⁶ to 2 x 10⁻³ mol per mol of silver halide is particularly effective.

The light-sensitive material produced by the process of the present invention need only have at least one silver halide emulsion layer, that is, one of a blue-sensitive layer, a green-sensitive layer and a red-sensitive layer, formed on a support. The number or order of the silver halide emulsion layers and the non-light-sensitive layers are not particularly limited. A typical example is a silver halide photographic light-sensitive material having at least one unit light-sensitive layer on a support constituted by a plurality of silver halide emulsion layers sensitive to substantially the same color but having different sensitivities or speeds. The unit light-sensitive layer is sensitive to blue, green or red light. In a multilayer color photographic silver halide light-sensitive material, the unit light-sensitive layers are generally arranged such that red, green and blue-sensitive layers are formed on one side of the support. in the order given. However, this order can be reversed or a layer with a different color sensitivity can be inserted between layers with the same color sensitivity according to the application.

Non-photosensitive layers such as various types of interlayers may be formed between the photosensitive silver halide layers and as top layer and bottom layer.

The intermediate layer may contain, for example, couplers and DIR compounds as described in JP-A-61-43748, JP-A-59-113438, JP-A-59-113440, JP-A-61-20037 and JP-A-61-20038 or a color mixing inhibitor which is normally used.

As a plurality of silver halide emulsion layers constituting each unit light-sensitive layer, a two-layer structure of high- and low-sensitivity emulsion layers as described in German Patent No. 1,121,470 or British Patent No. 923,045 may preferably be used. In this case, the layers are preferably arranged such that the sensitivity or speed decreases sequentially toward the support, and a non-light-sensitive layer may be formed in the silver halide emulsion layers. In addition, as described in JP-A-57-112751, JP-A-62-200350, JP-A-62-206541 and JP-A-62-206543, layers may be arranged such that a low-sensitivity emulsion layer is formed remote from the support and a high-sensitivity layer is formed close to the support.

More specifically, layers can be arranged from the farthest side from the substrate in an order of low sensitivity blue sensitive layer (BL)/high sensitive blue sensitive layer (BH)/high sensitive green sensitive layer (GH)/low sensitive green sensitive layer (GL)/high sensitive red sensitive layer (RH)/low sensitive red sensitive layer (RL), an order of BH/BL/GL/GH/RH/RL or an order of BH/BL/GH/GL/RL/RH.

In addition, layers as described in JP-B-55-34932 may be arranged in an order of blue-sensitive layer/GH/RH/GL/RL from the farthest side from the support. In addition, layers as described in JP-B-56-25738 and JP-B-62-63936 may be arranged in an order of blue-sensitive layer/GL/RL/GH/RH from the farthest side from the support.

As described in JP-B-49-15495, three layers may be arranged such that a silver halide emulsion layer having the highest sensitivity is arranged as an upper layer, a silver halide emulsion layer having a lower sensitivity than the upper layer is arranged as an intermediate layer, and a silver halide emulsion layer having a lower sensitivity than the intermediate layer is arranged as a lower layer. In other words, three layers having different sensitivities or speeds may be arranged such that the sensitivity decreases sequentially toward the support. When a layer structure is constructed by three layers having different sensitivities or speeds, these layers may be arranged in an order of medium-sensitive emulsion layer/high-sensitive emulsion layer/low-sensitive emulsion layer from the far side of the support in a layer having the same color sensitivity as described in JP-A-59-202464.

Also, an order of high-sensitivity emulsion layer/low-sensitivity emulsion layer/medium-sensitivity emulsion layer or low-sensitivity emulsion layer/medium-sensitivity emulsion layer/high-sensitivity emulsion layer can be adopted. In addition, the arrangement can be changed as described above even if 4 or more layers are formed.

As described above, different layer configurations and arrangements can be selected according to the application of the photosensitive material.

Not only the additives described above, but also other additives are used in the photosensitive material of the present invention, according to the application of the material.

These additives are described in Research Disclosure, Item 17643 (December 1978), Research Disclosure, Item 18716 (November 1979) and Research Disclosure, Item 308119 (December 1998), as listed in the following table:

In order to prevent the deterioration of the photographic properties caused by formaldehyde gas, a process as described in US Patents 4,411,987 or 4,435,503 is used. A compound that can react with formaldehyde and fix it is preferentially added to the light-sensitive material.

Various color couplers can be used in the present invention, and specific examples of these couplers are described in the patents mentioned in the above-mentioned RD No. 17643, VII-C to VII-G and RD No. 308119, VII-C to VII-G.

Preferred examples of yellow couplers are described, for example, in US Patents 3,933,501, 4,022,620, 4,326,024, 4,401,752 and 4,248,961, JP-B-58-10739, GB Patents 1,425,020 and 1,476,760, US Patents 3,973,968, 4,314,023 and 4,511,649 and EP-A-249,473.

Examples of a magenta coupler are preferably compounds of the 5-pyrazolone type and pyrazoloazole type and particularly preferably compounds which, for example, B. are described in U.S. Patents 4,310,619 and 4,351,897, EP-B-73,636, U.S. Patents 3,061,432 and 3,725,067, RD No. 24220 (June 1984), JP-A-60-33552, RD No. 24230 (June 1984), JP-A-60-43659, JP-A-61-72238, JP-A-60-35730, JP-A-55-118034, JP-A-60-185951, U.S. Patents 4,500,630, 4,540,654 and 4,556,630 and WO88/04795.

Examples of a cyan coupler are those of the phenol type and naphthol type. Among these, those are preferred which, for example, B. are described in US patents 4 052 212, 4 146 396, 4 228 233, 4 296 200, 2 369 929, 2 801 171, 2 772 162, 2 895 826, 3 772 002, 3 758 308, 4 343 011 and 4 327 173, DE-OS 33 29 729, EP-A-121 365 and EP-A-249 453, US patents 3 446 622, 4 333 999, 4 775 616, 4 451 559, 4 427 767, 4 690 889, 4 254 212 and 4 296 199 and JP-A-61-42658.

Typical examples of a polymerized dye-forming coupler are described, for example, in US Patents 3,451,820, 4,080,211, 4,367,282, 4,409,320 and 4,5676,910, British Patent 2,102,173 and EP-A-341,188.

Preferred examples of a coupler capable of forming colored dyes with adequate diffusibility are those described in US-PS 4,366,237, GB-PS 2,125,570, EP-B-96,570 and DE-OS 32 34 533.

Preferred examples of a colored coupler for correcting unnecessary absorption of a colored dye are those described in RD No. 17643, VII-G, RD No. 307105, VII-G, U.S. Patent No. 4,163,670, JP-B-57-39413, U.S. Patent Nos. 4,004,929 and 4,138,258, and British Patent No. 1,146,368. A coupler for correcting unnecessary absorption of a colored dye by a fluorescent dye released upon coupling described in U.S. Patent No. 4,774,181 or a coupler of a dye precursor group capable of reacting with a developer to form a dye as a releasing group described in U.S. Patent No. 4,777,120 can be preferably used.

Those compounds which release a photographically useful moiety upon coupling can also be preferably used in the present invention. DIR couplers, i.e., couplers which release a development inhibitor, are preferably those described in the patents cited in the above-described RD No. 17643, VII-F and RD No. 307105, VII-F, JP-A-57-151944, JP-A-57-154234, JP-A-60-184248, JP-A-63-37346, JP-A-63-37350 and U.S. Patent Nos. 4,248,962 and 4,782,012.

Preferred examples of a coupler which imagewise releases a nucleating agent or a development accelerator are preferably those described in British Patents 2,097,140 and 2,131,188, JP-A-59-157638 and JP-A-59-170840. In addition, compounds which release, for example, an antifoggant, a development accelerator or a silver halide solvent upon redox reaction with an oxidized form of a developing agent described in JP-A-60-107029, JP-A-60-252340, JP-A-1-44940 and JP-A-1-45687 can also be preferably used.

Examples of other compounds that can be used in the preparation of the light-sensitive material in the present invention are competitive couplers described, for example, in U.S. Patent No. 4,130,427; polyequivalent couplers described, for example, in U.S. Patent Nos. 4,283,472, 4,338,393 and 4,310,618; a DIR redox compound-releasing coupler, a DIR coupler-releasing coupler, a DIR coupler-releasing redox compound or a DIR redox-releasing redox compound described, for example, in JP-A-60-185950 and JP-A-62-24252; Dye-releasing couplers that restore color after release described in EP-A-173 302 and EP-A-313 308; a ligand-releasing coupler described in, for example, U.S. Patent No. 4,553,477; a leuco-dye-releasing coupler described in JP-A-63-75747; and a fluorescent-dye-releasing coupler described in U.S. Patent No. 4,774,181.

The couplers for use in this invention can be introduced into the light-sensitive material by various known dispersion methods.

Examples of a high boiling organic solvent that can be used in the oil-in-water dispersion process are described, for example, in US Pat. No. 2,322,027. Examples of a high boiling organic solvent that can be used in the oil-in-water dispersion process and has a boiling point of 175ºC or higher at atmospheric pressure are phthalic acid esters (e.g. dibutyl phthalate, dicyclohexyl phthalate, di-2-ethylhexyl phthalate, decyl phthalate, bis(2,4-di-t-amylphenyl) phthalate, bis(2,4-di-tamylphenyl) isophthalate, bis(1,1-di-ethylpropyl) phthalate), phosphate or phosphonate esters (e.g. triphenyl phosphate, tricresyl phosphate, 2-ethylhexyldiphenyl phosphate, tricyclohexyl phosphate, tri-2-ethylhexyl phosphate, tridodecyl phosphate, tributoxyethyl phosphate, trichloropropyl phosphate and di-2-ethylhexylphenyl phosphonate), benzoate esters (e.g. B. 2-ethylhexyl benzoate, dodecyl benzoate and 2-ethylhexyl p- hydroxybenzoate), amides (e.g. N,N-diethyldodecanamide, N,N- diethyllaurylamide and N-tetradecylpyrrolidone), alcohols or phenols (e.g. isostearyl alcohol and 2,4-di-tert- amylphenol), aliphatic carboxylate esters (e.g. bis(2-ethylhexyl)sebacate, dioctyl azelate, glycerol tributyrate, isostearyl lactate and trioctyl citrate), an aniline derivative (e.g. N,N-dibutyl-2-butoxy-5-tert-octylaniline) and hydrocarbons (e.g. paraffin, dodecylbenzene and diisopropylnaphthalene). An organic solvent having a boiling point of about 30°C or more, and preferably 50 to about 160°C, can be used as the co-solvent. Typical examples of the co-solvent are ethyl acetate, butyl acetate, ethyl propionate, methyl ethyl ketone, cyclohexanone, 2-ethoxyethyl acetate and dimethylformamide.

Steps and effects of a latex dispersion process and examples of a dipping latex are described, for example, in US Pat. No. 4,199,363 and German Laid-Open Applications Nos. 2,541,274 and 2,541,230.

Various types of antiseptics and fungicides are preferably added to the color light-sensitive material prepared by the process of the invention. Typical examples of the antiseptics and the fungicides are phenethyl alcohol and 1,2-benzisothiazolin-3-one, n-butyl phydroxybenzoate, phenol, 4-chloro-3,5- dimethylphenol, 2-phenoxyethanol and 2-(4-thiazolyl)benzimidazole, which are described in JP-A-63-257747, JP-A-62-272248 and JP-A-1-80941.

The present invention can be applied to various color photosensitive materials. Examples of the material are a color negative film for general purposes or for a motion picture film, a color reversal film for a slide or television, a color paper, a color positive film and a color reversal paper. In addition, the present invention is effectively applied to a film unit equipped with a lens disclosed in JP-B-2-32615 or Japanese Examined Utility Model Publication (JU-B) 3-39782.

A carrier which can be suitably used in the present invention is described, for example, in RD No. 17643, page 28, RD No. 18716, page 647, right column to page 648, left column, and RD No. 307105, page 879.

In the light-sensitive material produced by the process of the present invention, the A total sum of the film thicknesses of all the hydrophilic colloid layers on the emulsion layer side is preferably 28 µm or less, particularly preferably 23 µm or less, much more preferably 18 µm or less, and most preferably 16 µm or less. A film swelling rate T1/2 is preferably 30 seconds or less, and particularly preferably 20 seconds or less. The film thickness means a film thickness measured under a humidity conditioning at a temperature of 25°C and a relative humidity of 55% (2 days). The film swelling rate T1/2 can be measured according to a method known in the art. For example, the film swelling rate T1/2 can be measured using a "Swello meter" described by A. Green et al. in Photographic Science & Engineering, Vol. 19, No. 2, pages 124 to 129. If 90% of the maximum source film thickness achieved by performing a treatment using a color developer at 30ºC for 3 minutes and 15 seconds is defined as a saturated film thickness, T1/2 is defined as the time required to reach 1/2 of the saturated film thickness.

The film swelling rate T1/2 can be adjusted by adding a film hardener to gelatin as a binder or by changing the aging conditions after application. The swelling ratio is preferably 150 to 400%. The swelling ratio is calculated from the maximum swelling film thickness measured under the above conditions according to the following relationship:

(Maximum swelling film thickness - film thickness)/film thickness.

In the preparation of the light-sensitive material in the present invention, a hydrophilic colloid layer (so-called back layer) having a total dried film thickness of 2 to 20 µm is preferably formed on the side opposite to the side having emulsion layers. The back layer preferably contains, for example, the light absorber, filter dye, UV absorber, antistatic agent, film hardener, binder, plasticizer, lubricant, coating aid and surfactant described above. The swelling ratio of the back layer is preferably 150 to 500%.

The color photographic light-sensitive material prepared in the present invention can be developed by conventional methods described in RD No. 17643, pages 28 and 29 and RD No. 18716, page 651, left to right columns, and RD No. 307105, pages 880 and 881.

A color developer used in the development of the light-sensitive material prepared in the present invention is an aqueous alkaline solution containing, as a main component, preferably an aromatic primary amine as a color developer. Although an aminophenol compound is effective, a p-phenylenediamine compound is preferably used as the color developer. Typical examples of the p-phenylenediamine compound are: 3-methyl-4-amino-N,N-diethylaniline, 3-methyl-4-amino-N-ethyl-N-β-hydroxyethylaniline, 3-methyl-4-amino-N-ethyl-N-β-methanesulfonamidoethylaniline, 3-methyl-4-amino-N-ethyl-N-β-methoxyethylaniline, and the sulfates, hydrochlorides and p-toluenesulfonates thereof. Of these compounds, 3-methyl-4-amino-N-ethyl-N-β-hydroxyethylaniline and sulfates are particularly preferred. The above compounds can be used in a combination of two or more thereof according to the application.

Generally, the color developer contains a pH buffering agent, such as a carbonate, borate or phosphate of an alkali metal, and a development retarder or an antifoggant such as a chloride, bromide, iodide, benzimidazole, benzothiazole or a mercapto compound. If necessary, the color developer may also contain a preservative such as hydroxylamine, diethylhydroxylamine, a sulfite, a hydrazine such as N,N- biscarboxymethylhydrazine, a phenylsemicarbazide, triethanolamine or a catecholsulfonic acid; an organic solvent such as ethylene glycol or diethylene glycol; a development accelerator such as benzyl alcohol, polyethylene glycol, a quaternary ammonium salt or an amine; a dye-forming coupler; a competing coupler; an auxiliary developing agent such as 1-phenyl-3-pyrazolidone; a viscosity-imparting agent; and a complexing agent such as an aminopolycarboxylic acid, an aminopolyphosphonic acid, an alkylphosphonic acid or a phosphonocarboxylic acid. Examples of the complexing agent are ethylenediaminetetraacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, cyclohexanediaminetetraacetic acid, hydroxyethyliminodiacetic acid, 1-hydroxyethylidene-1,1- diphosphonic acid, nitrilo-N,N,N-trimethylenephosphonic acid, ethylenediamine,N,N,N',N'-tetramethylenephosphonic acid and ethylenediamine-di(o-hydroxyphenylacetic acid) and salts thereof.

To perform the reversal development, a black/white development is carried out and then the Color development is carried out. As the black-and-white developer, a well-known black-and-white developer such as a dihydroxybenzene such as hydroquinone, a 3-pyrazolidone such as 1-phenyl-3-pyrazolidone, and an aminophenol such as N-methyl-p-aminophenol can be used singly or in a combination of two or more thereof. The pH of the color and black-and-white developer is generally 9 to 12. Although the amount of the replenisher of the developers depends on the color photographic light-sensitive material to be processed, it is generally 3 L or less per m² of the light-sensitive material. The amount of the replenisher can be reduced to 500 ml or less by reducing the bromide ion concentration in the replenisher. When the amount of the replenisher is reduced, the contact area of the processing tank with air is preferably reduced to prevent evaporation and oxidation of the solution upon contact with air.

The contact area of the processing solution with air in a processing tank can be represented by the opening defined below:

Opening = [contact area (cm²) of the processing solution with air]/[volume (cm³) of the solution]

The above opening is preferably 0.1 or less, and more preferably 0.001 to 0.05. In order to reduce the opening, a shielding member such as a floating cover may be provided on the surface of the photographic processing solution in the processing tank. In addition, a method of using a movable cover described in JP-A-1-82033 or a slit developing method described in JP-A-63-216050. The aperture is preferably reduced not only in color and black/white development steps, but also in all subsequent steps such as bleaching, bleach-fixing, fixing, washing and stabilizing. In addition, the amount of replenisher can be reduced by using an agent for suppressing the accumulation of bromide ions in the developing solution.

The color development time is normally 2 to 5 minutes. However, the processing time can be shortened by setting a high temperature and high pH and using the color developer with high concentration.

The photographic emulsion layer is generally subjected to bleaching after color development. Bleaching may be carried out either simultaneously with fixing (bleach-fixing) or independently. In addition, bleach-fixing may be carried out after bleaching to increase the processing speed. Also, processing may be carried out in a bleach-fixing bath having two continuous tanks, fixing may be carried out before bleach-fixing, or bleaching may be carried out after bleach-fixing, according to application. Examples of the bleaching agent are compounds of a polyvalent metal, e.g. iron (III); peracids, quinones; and nitro compounds. Typical examples of the bleaching agent are an organic complex salt of iron (III), e.g. a complex salt with an aminopolycarboxylic acid such as ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, Cyclohexanediaminetetraacetic acid, methyliminodiacetic acid and 1,3-diaminopropanetetraacetic acid and glycol ether diaminetetraacetic acid; or a complex salt with citric acid, tartaric acid or malic acid. Of these compounds, a ferric complex salt of an aminopolycarboxylic acid such as a ferric complex salt of ethylenediaminetetraacetic acid or 1,3-diaminopropanetetraacetic acid is preferred because it can increase the processing speed and avoid environmental pollution. The ferric complex salt of an aminopolycarboxylic acid is useful in both the bleaching and bleach-fixing solution. The pH of the bleaching or bleach-fixing solution using the ferric complex salt of an aminopolycarboxylic acid is normally 4.0 to 8. However, in order to increase the processing speed, the processing may be carried out at a lower pH.

A bleach accelerator can be used in the bleach solution, the bleach-fix solution and their prebath if required. Examples of a useful bleach accelerator are: compounds containing a mercapto group or a disulfide group, described e.g. e.g., in U.S. Pat. No. 3,893,858 and German Pat. Nos. 1,290,812 and 2,059,988, JP-A-53-32736, JP-A-53-57831, JP-A-53-37418, JP-A-53-72623, JP-A-53-95630, JP-A-53-95631, JP-A-53-104232, JP-A-53-124424, JP-A-53-141623, JP-A-53-28426 and RD No. 17129 (July 1978); thiazolidine derivatives described in JP-A-50-140129; Thiourea derivatives described in JP-B-45-8506, JP-A-52-20832, JP-A-53-32735 and US-PS 3 706 561; iodide salts described in DE-PS 11 27 715 and JP-A-58-16235; polyoxyethylene compounds described in DE-PS 966 410 and 2 748 430; polyamine compounds described in JP-B-45-8836; those described in JP-A-49-40943, JP-A-49-59644, JP-A-53-94927, JP-A-54-35727, JP-A-55-26506 and JP-A-58-163940; and a bromide ion. Of these compounds, a compound having a mercapto group or a disulfide group is preferred because the compound has a strong accelerating effect. In particular, the compounds described in U.S. Patent No. 3,893,858, German Patent No. 1,290,812 and JP-A-53-95630 are preferred. A compound described in U.S. Patent No. 4,552,834 is also preferred. These bleaching accelerators can be added to the light-sensitive material. These bleaching accelerators are useful especially in bleach-fixing a color photographic light-sensitive material.

The bleaching solution or the bleach-fixing solution preferably contains, in addition to the above compounds, an organic acid to prevent bleach stains. The most preferred organic acid is a compound having an acid dissociation constant (pKa) of 2 to 5, e.g. acetic acid, propionic acid or hydroxyacetic acid.

Examples of the fixing agent used in the fixing solution or the bleach-fixing solution are a thiosulfate salt, a thiocyanate salt, a thioether-based compound, a thiourea and a large amount of an iodide. Of these compounds, a thiosulfate, especially ammonium thiosulfate, can be used in the widest range of applications. In addition, a combination of a thiosulfate with a thiocyanate, a thioether-based compound or thiourea is preferably used. As a preservative of the fixing solution or the bleach-fixing solution, a sulfite, a bisulfite, a carbonyl-bisulfite adduct or a sulfinic acid compound described in EP-A-294 769 is preferred. In addition, various types of aminopolycarboxylic acids are preferably used. or organic phosphonic acids are added to the solution to stabilize the fixing solution or bleach-fixing solution.

In the present invention, 0.1 to 10 mol/L of a compound having a pKa of 6.0 to 9.0 is preferably added to the fixing solution or bleach-fixing solution to adjust the pH. Preferred examples of the compound are imidazoles such as imidazole, 1-methylimidazole, 1-ethylimidazole and 2-methylimidazole.

The total time of the desilvering step is preferably as short as possible as long as no desilvering failure occurs. A preferred time is one to three minutes, and preferably one to two minutes. The processing temperature is 25 to 50ºC, and preferably 35 to 45ºC. Within the preferred temperature range, the desilvering speed is increased, and the formation of a stain after processing can be effectively prevented.

In the desilvering step, stirring is preferably as strong as possible. Examples of a method for intensifying stirring are a method of impinging a jet of the processing solution against the emulsion surface of the photosensitive material described in JP-A-62-183460, a method of increasing the stirring effect using a rotating means described in JP-A-62-183461, a method of moving the photosensitive material while bringing the emulsion surface into contact with a wiping blade provided in the solution to cause a disturbance on the emulsion surface to thereby improve the stirring effect, and a method of increasing the circulation amount in the entire processing solution. Such a stirring-improving method Agent is effective in any of the bleaching solution, the bleach-fixing solution and the fixing solution. It is believed that the improvement in stirring increases the speed of supplying the bleaching agent and fixing agent into the emulsion film, resulting in an increase in the desilvering speed. The above stirring improving agent is more effective when the bleaching accelerator is used, that is, it significantly increases the accelerating speed or eliminates fixation disturbance caused by the bleaching accelerator.

An automatic developing machine for processing the photosensitive material produced in the present invention preferably has a transport means for the photosensitive material described in JP-A-60-191257, JP-A-60-191258 or JP-A-60-191259. As described in JP-A-60-191257, this transport means can significantly reduce the carryover of the processing solution from a pre-bath to a post-bath, thereby effectively preventing the deterioration of the performance of the processing solution. This effect significantly shortens, especially, the processing time in each processing step and reduces the amount of the replenisher for the processing solution.

The photographic light-sensitive material prepared in the present invention is normally subjected to a washing and/or stabilizing step after desilvering. The amount of water used in the washing step can be arbitrarily set in a wide range according to the properties (e.g., the properties used by the substances such as the coupler) of the light-sensitive material, the application of the material, the temperature of the water, the number of water tanks (the number of stages), the refreshment pattern which is a cocurrent or countercurrent, and other conditions. The relationship between the amount of water and the number of water tanks in a multi-stage countercurrent pattern can be obtained by a method described in "Journal of the Society of Motion Picture and Television Engineering", vol. 64, pp. 248 to 253 (May 1955). In the multi-stage countercurrent pattern disclosed in this reference, the amount of water used for washing can be greatly reduced. However, since the washing water remains in the tanks for a long period of time, bacteria may proliferate and floating substances may adversely adhere to the photosensitive material. To solve this problem in the process of the color photographic photosensitive material of the present invention, a method of reducing calcium and magnesium ions as described in JP-A-62-288838 can be effectively used. In addition, an antibacterial agent such as an isothiazolone compound and a cyanabazole described in JP-A-57-8542, a chlorine-based antibacterial agent such as chlorinated sodium isocyanurate, and antibacterial agents such as benzotriazole described in Hiroshi Horiguchi et al., "Chemistry of Antibacterial and Antifungal Agents" (1986), Sankyo Shuppan, Eiseigijutsu-Kai, editors, "Sterilization, Antibacterial and Antifungal Techniques for Microorganisms" (1982), Kogyogijutsu-Kai and Nippon Bokin Bobai Gakkai, editors, "Dictionary of Antibacterial and Antifungal Agents" (1986) can be used.

The pH of the water for washing the photographic light-sensitive material prepared in the present invention is 4 to 9, and preferably 5 to 8. The Water temperature and washing time may vary according to the properties and applications of the photosensitive material. Normally, the washing time is 20 seconds to 10 minutes at a temperature of 15 to 45°C, and preferably 30 seconds to 5 minutes at 25 to 40°C. The photosensitive material of the present invention can be directly processed by a stabilizing agent instead of washing in water. Any of the known methods described in JP-A-57-8543, JP-A-58-14834 and JP-A-60-220345 can be used in such stabilization processing.

In some cases, stabilization is carried out after washing. An example is a stabilizing bath containing a dye-stabilizing agent and a surfactant to be used as a final bath for the color photographic light-sensitive material. Examples of the dye-stabilizing agent are an aldehyde such as formalin or glutaraldehyde, an N-methylol compound, hexamethylenetetramine and an adduct of aldehyde sulfite. Various complexing agents and fungicides can be added to the stabilizing bath.

The excess solution generated during washing and/or replenishment of the stabilization solution can be reused in another step such as the desilvering step.

In processing using an automatic developing machine or the like, it is preferable to add water for correcting the concentration if each processing solution described above is concentrated by evaporation.

The silver halide color light-sensitive material prepared in the present invention may contain a color developer in order to simplify processing and increase processing speed. For this purpose, various types of color developer precursors can be preferably used. Examples of the precursor are an indoaniline-based compound described in U.S. Patent No. 3,342,597, Schiff's bases described in U.S. Patent No. 3,342,599 and RD Nos. 14850 and 15159, an aldol compound described in RD Nos. 13924, a metal salt complex described in U.S. Patent No. 3,719,492, and a urethane-based compound described in JP-A-53 135628.

The silver halide color light-sensitive material prepared in the present invention may contain various 1-phenyl-3-pyrazolidones to accelerate color development if necessary. Typical examples of the compound are described in JP-A-56-64339, JP-A-57-144547 and JP-A-58-115438.

Each processing solution in the present invention is used at a temperature of 10 to 50°C. Although the normal processing temperature is 33 to 38°C, the processing can be accelerated at a higher temperature to shorten the processing time, or the image quality or stability of the processing solution can be improved at a lower temperature.

In addition, the silver halide photosensitive material prepared in the present invention can also be used as a heat-developing photosensitive material, as described in, for example, US-PS 4,500,626, JP-A-60-133449, JP-A-59-218443, JP-A-61-238056 and EP-A2-210 660.

The silver halide color photosensitive material prepared in the present invention exerts its advantages particularly effectively when used in a lens-equipped film unit disclosed in JP-B-2-32615 or Japanese Examined Published Utility Model Application (JU-B) 3-39782.

EXAMPLES

The present invention will be described in more detail below by means of examples, but the invention is not limited to these examples.

EXAMPLE 1

Four types of seed crystals H to K were prepared, which had a volume-weighted equivalent sphere diameter of 0.40 µm. The seed crystals (H) were irregular, potato-like grains and had a relatively broad size distribution (coefficient of variation: 18%). The seed crystals (I) were octahedral grains with rounded corners [85% of the surface was a (111) face] and had a narrow size distribution (coefficient of variation: about 12%). The seed crystals (J) were tetradecahedral grains [50% of the surface was a (111) face] and had a relatively broad size distribution (coefficient of variation: 15%). The seed crystals (K) were cubic grains with broken corners [80% of the surface was a (100) face] and had a narrower size distribution (coefficient of variation: 8%) than all other seeds prepared. Seeds (H) to (K) were all silver bromoiodide grains formed for an average iodide content of 2 mol%.

These seed crystals were dissolved in 15 t of distilled water, and the resulting solution was heated to 60°C and vigorously stirred after adjusting the silver potential (vs. SCE) and pH to -20 mV and 5, respectively. Next, a high iodide layer was grown on each seed crystal by selecting one of the conditions (A) to (G) specified below, and the silver potential and pH were again adjusted to -20 mV and 5. After that, the solution was heated to 75°C, thereby growing a low iodide layer on the seed crystal (iodide content 1 mol%). As a result, emulsions (L) to (X) shown in Table 3 (presented later) were prepared, of which two contained potato-like grains with a diameter of 0.5 µm, five contained octahedral grains [80% of the surface was a (111) face], two contained tetradecahedral grains [50% of the surface was a (111) face], and the remaining five contained cubic grains [85% of the surface was a (100) face]. In each grain of each emulsion thus prepared, the seed crystal, the high iodide layer, and the low iodide layer had silver amounts in the ratio of 50:5:45.

Conditions for growing the high iodide layer:

(A) 5% aqueous potassium iodide was continuously added to the solution for 10 minutes.

(B) An emulsion containing fine AgI grains with a diameter of 0.02 µm was added to the solution and completely dissolved during 10 min.

(C) An aqueous solution of an iodide ion-releasing agent (compound (11)) was added to the solution, an aqueous NaOH solution was added, and iodide ions were released from compound (11) over 10 minutes while the pH was controlled in the range of 5.0 to 8.5 (the pH was controlled such that 50% of compound (11) released iodide ions within 5 minutes from the start of the pH increase).

(D) Method (D) was performed following the same procedures as described for method (C) above, with the following exception.

The iodide ions were released from compound (11) during 4 minutes while the pH was controlled in the range of 5.0 to 9.5 instead of 5.0 to 8.5 (the pH was controlled such that 50% of compound (11) released the iodide ions within 2 minutes from the beginning of the pH increase).

(E) An aqueous solution of an iodide ion-releasing agent (compound (58)) was added to the solution, an aqueous sodium p-toluenesulfinate solution (3-fold molar) was added to the solution, and iodide ions were released from compound (58) over 10 minutes. (Iodide ions were released from 50% of compound (58) within 10 seconds from the time of adding p-toluenesulfinate to the solution.) (F) Method (F) was performed following the same procedures as described for method (E) above, with the following exception.

After adding an aqueous sodium sulfite solution (1.2 times molar) instead of the aqueous sodium p-toluenesulfinate solution (3 times molar), an aqueous NaOH solution was added to the solution, thereby raising the pH to 9.0, iodide ions were released from the compound (58) within 8 minutes while the pH was maintained at 9.0 and then returned to 5.0. (Iodide ions were released from 50% of the compound (58) within 5 seconds from the time of raising the pH to 9.0.)

The rate of iodide ion release was measured using the following procedure.

First, the emulsion grains of the solution were separated by centrifugal separation. Next, the amount of unreacted iodide ion releasing agent contained in the supernatant liquid was determined by ICP (inductively coupled plasma emission) analysis. Then, the rate of iodide ion release was measured from the changes in the amount of unreacted iodide ion releasing agent.

Each of the emulsions (L) to (X) was desalted and then redispersed, adjusting the pH and pAg to 6.0 and 8.8, respectively. Thereafter, the emulsions (L) to (Y) were subjected to optimal chemical sensitization using the chemical sensitizer thiocyanic acid, selenocyanic acid, chloroauric acid, thiosulfonic acid and selenourea in the presence of the Spectral sensitizing dyes ExS-1, -2 and -3 and compounds F-6, F-12 and F-14.

The emulsions were coated onto triacetyl cellulose film supports with underlying layers in the amounts shown in Table 1 to produce coated samples containing the emulsion and a protective layer. TABLE 1 1. Emulsion coating conditions

These samples were left at a temperature of 40ºC and a relative humidity of 70% for 14 hours, exposed through a continuous wedge for 1/100 second and subjected to the color development specified below:

2. Exposure and processing conditions:

The densities of the processed samples were measured through a green filter.

The compositions of the individual processing solutions are given below.

Color developing solution (g)

Diethylenetriaminepentaacetic acid 2.0

1-Hydroxyethylidene-1,1-diphosphonic acid 3.0

Sodium sulphite 4.0

Potassium carbonate 30.0

Potassium bromide 1.4

Potassium iodide 1.5 mg

Hydroxylamine sulfate 2,4

4-(N-Ethyl-N-β-hydroxylethylamino)-2-methylaniline sulfate 4.5

Water to 1.0 l

pH10.05

Bleach-fixing solution:

This solution had the composition specified in Table 2. TABLE 2

Watering solution:

Tap water was introduced into a mixed bed column filled with a strong acidic H-type cation exchange resin (Amberlite IR-120B, available from Rohm & Haas Co.) and a strong basic OH-type anion exchange resin (Amberlite IR-400) to adjust the concentrations of calcium and magnesium to 3 mg/L or less. Then, 20 mg/L of sodium isocyanurate dichloride and 1.5 g/L of sodium sulfate were added.

The pH of the solution fell in the range of 6.5 to 7.5.

Stabilization solution: (g)

Formalin (37%) 2.0 ml

Polyoxyethylene p-monononylphenyl ether (average degree of polymerization = 10) 0.3

Disodium ethylenediaminetetraacetate 0.05

Water to 1.0 l

pH 5.0-8.0

The sensitivity is represented by a relative value of the logarithm of the reciprocal of the amount of exposure (lux s) at which a density of fog + 0.2 is obtained.

The results obtained are summarized in Table 3. TABLE 3

As can be seen from Table 3, the inventive samples had low fog and high sensitivity.

EXAMPLE 2

Emulsions (L'), (M'), (P'), (R'), (U') and (Y') each containing small grains having a diameter of 0.3 µm were prepared in the same manner as the emulsions (L), (M), (P), (R), (U) and (Y) of Example 1 except that seed crystals having a diameter of 0.24 µm were used. A plurality of layers having the compositions shown below were coated on undercoated triacetylcellulose film supports to prepare various multilayer photosensitive materials. The emulsions (A) and (B) used in the third layer of one of the samples were replaced by the emulsions (L) and (L'), respectively, to prepare sample (101). Similarly, the emulsions (A) and (B) used in the third layer of five other samples were replaced by the emulsions (M) and (M'), the emulsions (P) and (P'), the emulsions (R) and (R'), the emulsions (U) and (U'), and the emulsions (Y) and (Y'), thereby preparing the samples (102), (103), (104), (105), and (106).

Compositions of the light-sensitive layers:

The main materials used in the individual layers are classified as follows:

ExC: Blue-green coupler

ExM: Purple Coupler

ExY: Yellow coupler

ExS: Sensitizing dye

UV: UV absorber

HBS: high boiling organic solvent

H: Gelatin hardener

The number corresponding to each component indicates the coating amount in units of g/m². The coating amount of a silver halide is represented by the coating amount of silver. The coating amount of each sensitizing dye is represented in units of mol/mol of silver halide in the same layer.

Sample (101): 1st layer: anti-halation layer

Black colloidal silver Silver 0.18

Gelatine 1.40

ExM-1 0.18

ExF-1 2.0 · 10⊃min;³

2nd layer: intermediate layer

Emulsion G Silver 0.065

2,5-Di-t-pentadecylhydroquinone 0.18

ExC-2 0.020

W-1 0.060

W-2 0.080

W-3 0.10

HBS-1 0.10

HBS-2 0.020

Gelatin 1.04

3rd layer: low-sensitivity red-sensitive emulsion layer

Emulsion A Silver 0.25

Emulsion B Silver 0.25

ExS-1 6.9 · 10⊃min;⊃5;

ExS-2 1.8 · 10⊃min;⊃5;

ExS-3 3.1 · 10⊃min;⊃4;

ExC-1 0.17

ExC-4 0.17

ExC-7 0.020

W-1 0.070

W-2 0.050

W-3 0.070

HBS-1 0.60

Gelatin 0.87

4th layer: medium-sensitive red-sensitive emulsion layer

Emulsion D Silver 0.80

ExS-1 3.5 · 10⊃min;⊃4;

ExS-2 1.6 · 10⊃min;⊃5;

ExS-3 5.1 · 10⊃min;⊃4;

ExC-1 0.20

ExC-2 0.050

ExC-4 0.20

ExC-5 0.050

ExC-7 0.015

W-1 0.070

W-2 0.050

W-3 0.070

Gelatine 1.30

5th layer: highly sensitive red-sensitive emulsion layer

Emulsion E Silver 1.40

ExS-1 2.4 · 10⊃min;⊃4;

ExS-2 1.0 · 10⊃min;⊃4;

ExS-3 3.4 · 10⊃min;⊃4;

ExC-1 0.097

ExC-2 0.010

ExC-3 0.065

ExC-6 0.020

HBS-1 0.22

HBS-2 0.10

Gelatin 1.63

6th layer: intermediate layer

Cpd-1 0.040

HBS-1 0.020

Gelatin 0.80

7th layer: low-sensitivity green-sensitive emulsion layer

Emulsion C Silver 0.30

ExS-4 2.6 · 10⊃min;⊃5;

ExS-5 1.8 · 10⊃min;⊃4;

ExS-6 6.9 · 10⊃min;⊃4;

ExM-1 0.021

ExM-2 0.26

ExM-3 0.030

ExY-1 0.025

HBS-1 0.10

HBS-3 0.010

Gelatin 0.63

8th layer: medium-sensitive green-sensitive emulsion layer

Emulsion D Silver 0.55

ExS-4 2.2 · 10⊃min;⊃5;

ExS-5 1.5 · 10⊃min;⊃4;

ExS-6 5.8 · 10⊃min;⊃4;

ExM-2 0.094

ExM-3 0.026

ExY-1 0.018

HBS-1 0.16

HBS-3 8.0 · 10⊃min;³

Gelatin 0.50

9th layer: highly sensitive green-sensitive emulsion layer

Emulsion E Silver 1.55

ExS-4 4.6 · 10⊃min;⊃5;

ExS-5 1.0 · 10⊃min;⊃4;

ExS-6 3.9 · 10⊃min;⊃4;

ExC-1 0.015

ExM-1 0.013

ExM-4 0.065

ExM-5 0.019

HBS-1 0.25

HBS-2 0.10

Gelatin 1.54

10th layer: yellow filter layer

Yellow colloidal silver Silver 0.035

Cpd-1 0.080

HBS-1 0.030

Gelatin 0.95

11th layer: low-sensitivity blue-sensitive emulsion layer

Emulsion C Silver 0.18

ExS-7 8.6 · 10⊃min;⊃4;

ExY-1 0.042

ExY-2 0.72

HBS-1 0.28

Gelatin 1.10

12th layer: medium-sensitive blue-sensitive emulsion layer

Emulsion D Silver 0.40

ExS-7 7.4 · 10⊃min;⊃4;

ExC-7 7.0 · 10⊃min;³

ExY-2 0.15

HBS-1 0.050

Gelatin 0.78

13th layer: medium-sensitive blue-sensitive emulsion layer

Emulsion F Silver 0.70

ExS-7 2.8 · 10⊃min;⊃4;

ExY-2 0.20

HBS-1 0.070

Gelatin 0.69

14th layer: first protective layer

Emulsion G Silver 0.20

LTV-4 0.11

W-5 0.17

HBS-1 5.0 · 10⊃min;²

Gelatin 1.00

15th layer: second protective layer

H-Z 0.40

B-Z (diameter 1.7 um) 5.0 · 10⊃min;²

B-2 (diameter 1.7 um) 0.10

B-3 0.10

S-1 0.20

Gelatine 1.20

In addition to the above components, the individual layers contained W-1 to W-3, B-4 to B-6, F-1 to F-17, iron salt, lead salt, gold salt, platinum salt, iridium salt and rhodium salt to improve storage stability, processability, pressure resistance, antiseptic and anti-mold properties, antistatic properties and coating properties.

The emulsions represented by the symbols above are listed in Table 4 below. TABLE 4

In Table 4:

(1) Emulsions (C) to (F) were subjected to reduction sensitization during grain preparation by using thiourea dioxide and thiosulfonic acid according to the examples in JP-A-2-191938.

(2) The emulsions (C) to (F) were subjected to gold sensitization, sulfur sensitization and selenium sensitization in the presence of the spectral sensitizing dyes described in the individual photosensitive layers and sodium thiocyanate according to the examples in JP-A-3-237450.

(3) The preparation of tabular grains was carried out by using low molecular weight gelatin according to the examples in JP-A-1-158426.

(4) Dislocation lines as described in JP-A-2-34090 were observed in tabular grains and regular crystal grains with a grain structure when a high-voltage electron microscope was used.

The compounds used in the layers described above were as follows:

The samples (101) to (106) thus obtained were exposed and processed by the procedure specified below: PROCESSING PROCEDURE

The compositions of the individual processing solutions are given below.

Color developing solution: (g)

Diethylenetriaminepentaacetic acid 1.0

1-Hydroxyethylidene-1,1-diphosphonic acid 3.0

Sodium sulphite 4.0

Potassium carbonate 30.0

Potassium bromide 1.4

Potassium iodide 1.5 mg

Hydroxylamine sulfate 2,4

4-[N-Ethyl-N-β-hydroxylethylamino)-2-methylaniline sulfate 4.5

Water to 1.0 l

pH10.05 Bleaching solution (g)

Bleach-fixing solution: (g)

Iron(III) ammonium ethylenediamine tetraacetate dihydrate 50.0

Disodium ethylenediaminetetraacetate 5.0

Sodium sulphite 12.0

Aqueous ammonium thiosulfate solution (70%) 240.0 ml

Ammonia water (27%) 6.0 ml

Water to 1.0 l

pH7.2

Watering solution:

Tap water was introduced into a mixed bed column filled with a strong acidic H-type cation exchange resin (Amberlite IR-120B, available from Rohm & Haas Co.) and a strong basic OH-type anion exchange resin (Amberlite IR-400) to adjust the concentrations of calcium and magnesium to 3 mg/L or less. Then, 20 mg/L of sodium isocyanuric dichloride and 0.15 g/L of sodium sulfate were added. The pH of the solution fell within the range of 6.5 to 7.5.

Stabilization solution: (g)

Formalin (37%) 2.0 ml

Polyoxyethylene p-monononylphenyl ether (average degree of polymerization = 10) 0.3

Disodium ethylenediaminetetraacetate 0.05

Water to 1.0 l

pH 5.0-8.0

Samples (104) and (106) falling within the scope of the invention had higher sensitivity and higher gradation than comparative samples (101), (102), (103) and (105) in the high density region (density 1.5 or more) of the characteristic curve for the red-sensitive layer. It is apparent that the emulsions of the invention also impart excellent properties to a multilayer photosensitive material.

As described, the present invention can provide a silver halide photographic light-sensitive material which has high sensitivity and low fog and which has good photographic properties.

Claims (9)

1. A process for producing a silver halide photographic light-sensitive material, comprising Producing at least one light-sensitive silver halide emulsion comprising regular crystal grains with a silver halide phase containing silver iodide, Forming at least one emulsion layer containing the at least one light-sensitive silver halide emulsion on a support, characterized in that the silver halide phase is formed during the preparation of the light-sensitive silver halide emulsion, while iodide ions are rapidly generated in the reactor vessel, the iodide ions are generated from an iodide ion-releasing agent added to the reactor vessel, 50 to 100% of the iodide ion releasing agent completes the release of iodide ions within 180 continuous seconds in the reactor vessel and the iodide ions are generated by a reaction of an iodide ion releasing agent with an iodide ion release controlling agent, provided that if the iodide ion releasing agent is I(CH2)2COOH, the iodide ion releasing agent is not Br(CH2)2SO3Na. 2. The method according to claim 1, characterized in that 60% or more of the surface of each regular crystal grain is a (111) face. 3. The method according to claim 1, characterized in that 60% or more of the surface of each regular crystal grain is a (100) face. 4. A process according to claim 1, characterized in that the reaction is a second order reaction which is substantially proportional to the concentration of the iodide ion releasing agent and to the concentration of the iodide ion release controlling agent, and the rate constant of the second order reaction is 1,000 to 5 x 10⁻³ M⁻¹ s⁻¹. 5. Process according to claim 1, characterized in that the iodide ions are generated from an iodide ion-releasing agent represented by the formula (I): Formula (I): R-I where R represents a monovalent organic radical, which releases the iodine atom in the form of ions upon reaction with a base and/or a nucleophilic reagent. 6. Process according to claim 1, characterized in that the iodide ions are generated from an iodide ion-releasing agent represented by the following formula (II): Formula (II): wherein R₂₁ represents an electron withdrawing group, each R₂₂ represents a hydrogen atom or a substitutable group, and n₂ represents an integer of 1 to 6. 7. Process according to claim 1, characterized in that the iodide ion releasing agent is represented by the following formula (III): Formula (III): wherein R₃₁ represents an R₃₃O group, R₃₃S group, (R₃₃)₂N group, (R₃₃)₂P group or phenyl group, wherein R₃₃ represents a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an alkynyl group having 2 or 3 carbon atoms, an aryl group having 6 to 30 carbon atoms, an aralkyl group having 7 to 30 carbon atoms or a heterocyclic group having 4 to 30 carbon atoms, with the proviso that the two R33 groups may be the same or different when R31 represents the (R33)2N group or (R33)2P group; each R32 represents a hydrogen atom or a substitutable group; and n3 represents an integer of 1 to 6. 8. Process according to claim 1, characterized in that 50 to 100% of the number of all grains are occupied by regular crystal grains with 10 or more dislocation lines per grain. 9. Process according to claim 1, characterized in that the grains contain silver iodide with a coefficient of variation of the silver iodide content distribution between the grains of 3 to 20%.